Cdk-cylin complex and its effectors

Investigate Cdk-cyclin and its associating protein targets in cell cycle and cancer with highly cited reagents.

Cdk (cyclin-dependent kinase) associates with cyclins to play a crucial role in cell cycle progression. p21 directly binds to Cdk-cyclin complexes maintaining Cdk in an inactive state¹.

Inactive Cdk cannot phosphorylate downstream targets thereby leading to cell cycle arrest². 

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Contents

• Cdk1 (Cdc2, p34^Cdc2)
• Cyclin B1
• Cdk2 (CDKN2, p33)
• Cyclin E1
• Cyclin A1
• Cdc25c
• Cdc6
• Cdk4/6 and cyclin D1/D2
• Retinoblastoma protein (Rb)
• MDM2
• p21 cell cycle analysis

​​​Cdk1 (Cdc2, p34^Cdc2​)

Cdk1 interacts with cyclin B to form an active heterodimer³. Cdk1-cyclin B1 complex progresses the cell cycle through G2/M mitotic phase. Uncontrolled Cdk1 activation can lead to apoptosis².
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Type	Reagent name	Description	AbID
Antibody	Anti-CDK1 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: ICC/IF, Flow Cyt, WB, IP, IHC-P	ab133327
	Anti-CDK1 (phospho Y15) antibody	Y15: Phosphorylated inhibitory residue of Cdk1 causing G1 block4. Type: Rabbit polyclonal antibody Reactivity: Hu, Mo, Rt Applications: WB, ELISA	ab47594
	Anti-CDK1 (phospho T14) antibody	T14: Phosphorylated inhibitory residue of Cdk1 causing G1 block4. Type: Rabbit polyclonal antibody Reactivity: Hu, Mo, Rt Applications: WB, ELISA	ab58509
	Anti-CDK1 (phospho T161) antibody	T161: Phosphorylated residue that stabilizes Cdk-cyclin B1 complex5. Type: Rabbit polyclonal antibody Reactivity: Hu, Mo, Rt Applications: WB, ELISA	ab194874
Kit	CDK1 SimpleStep® ELISA kit	Get fast, reproducible results in 90 minutes. Reactivity: Hu Range: 93.75 pg/ml-6000 pg/ml Method: Colorimetric	ab212162
Small molecule compound	Ro-3306 (Cdk1 inhibitor)	Selective, reversible small molecule Cdk1 inhibitor (Ki = 35 nM Cdk1/cyclin B).	ab141491
	Bleomycin (G1/S, G2M blocker)	Induces cell cycle exit and down-regulation of mitotic cyclins. Causes increased accumulation of cyclin B1-Cdk1-p21 complexes2.	ab142977

Click here for the full list of Cdk inhibitors

Cyclin B1

​​Cyclin B1 levels rise during G2 phase facilitating Cdk1-cyclin B1 complex formation⁶. Cdk1-cyclin B1 is activated by Cdc25 phosphatase⁷.
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Type	Reagent name	Description	AbID
Antibody	Anti-Cyclin B1 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, Flow Cyt, ICC, IP	ab32053
	Anti-Cyclin B1 (p S126) antibody	S126-phosphorylated cyclin B1 binds to T57-phosphorylated p21. Promotes kinase activation and G2M progression8. Type: Rabbit monoclonal antibody Reactivity: Hu ​Applications: IP, WB	ab133439
Small molecule compound	Paclitaxel (Taxol)	Cyclin B1 suppression increases taxol sensitivity and inhibits tumor growth9.	ab120143
	Leptomycin B	Induces endogenous nuclear cyclin B1 accumulation and prevents nuclear export10.	ab120501

Click here for conjugated Cdk antibodies

Cdk 2 (CDKN2, p33)

Binding of p21 to Cdk2-cyclin E complex arrests cells at the G1/S checkpoint. Cdk2 inhibition by p21 is therefore crucial for DNA damage repair¹¹.

Type	Reagent name	Description	AbID
Antibody	Anti-Cdk2 antibody​	Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt Applications: ICC/IF, IP, WB, Flow Cyt, IHC-P	ab32147
	Anti-CDK2 (phospho Y15) antibody	Y15: Inhibitory phosphorylation site by Wee1 kinase12. Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt Applications: IHC-P, WB, IP	ab76146
	Anti-CDK2 (phospho T14) antibody	T14: Inhibitory phosphorylation site by Wee1 kinase12. Type: Rabbit monoclonal antibody Reactivity: Hu, Rt, ChHa Applications: WB, IP, IHC-P, ICC	ab68265
	Anti-CDK2 (phospho T160) antibody	T160: Phosphorylation that stabilizes the Cdk2-cyclin complex12. Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt ​Applications: IHC-P, WB	ab194868
Small molecule compound	Flavopiridol (Cdk2 inhibitor)	Potent inhibitor Cdk2 kinase activity (IC50 = 100 nM at 400 μM ATP)13.	ab141300
	Roscovitine (Cdk2 inhibitor)	Potent and selective inhibitor of Cdk2, Cdk5, Cdc2. Exhibits IC50 = 0.7 μM for Cdk2/cyclin A, Cdk2/cyclin E14.	ab141847

Cyclin E1 

Cdk2-cyclin E1 complex facilitates phosphorylation of retinoblastoma protein (Rb), E2F transcription factor release and DNA S phase entry¹⁵. 

Type	Reagent name	Description	AbID
Antibody	Anti-Cyclin E1 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt Applications: IHC-P, WB	ab33911
Small molecule compound	Sorafenib (kinase inhibitor)	Cyclin E1 expression is not suppressed in sorafenib-resistant cancer16.	ab141966

Cyclin A1

p53 activates cyclin A1 promoter. Cdk2-cyclin A1 complex functions in DNA double strand break repair¹⁷.

Type	Reagent name	Description	AbID
Antibody	Anti-Cyclin A1/A2 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, IP	ab185619
	Anti-Ku70 antibody	Ku70 is a Cdk2-cyclin A1 interactor that plays a role in DNA repair17. Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, ICC/IF, Flow Cyt, IP	ab92450

Cdc25c 

Cdc25 dephosphorylates Y15 and T14 on Cdk2, the rate-limiting step in Cdk activation/cell-cycle progression¹⁸.

Type	Reagent name	Description	AbID
Antibody	Anti-Cdc25C antibody​	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, ICC/IF, Flow Cyt, IP	ab32444
Small molecule compound	NSC 663284 (Cdc25 inhibitor)	Potent and selective inhibitor of Cdc25 (Ki = 89 nM for Cdc25C)19.	ab144408
	Gossypin (Cdc25 activator)	Induces G2/M arrest and inhibits cell proliferation via Chk1 phosphorylation of Cdc25C20.	ab145623
Lysate	Cdc25C lysate	Cdc25C overexpression 293T lysate suitable for WB as a control. Concentration: 100 µl at 1.7 mg/ml (1x sample buffer)	ab94219

Cdc6

Protein expression of Cdc6 increases during G1 phase. Cdc6 regulates initiation of DNA replication and its levels are stabilized by Cdk2-cyclin E activity²¹.

Type	Reagent name	Description	AbID
Antibody	Anti-Cdc6 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, ICC	ab109315
	Anti-Cdc6 (phospho S54) antibody	Phosphorylation on S54 prevents Cdc6 from APC/C-dependent proteolysis22. Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, ICC/IF	ab75809
	Anti-Cdc6 (phospho S106) antibody	Cdk2-Cyclin E phosphorylation site required to induce G2 arrest23. Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB	ab76422
	Anti-CRM1 antibody (Nuclear export factor)	CRM1 regulates Cyclin B1 nuclear export and localization10. Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt ​Applications: IHC-P, Flow Cyt, ICC/IF, WB	ab191081
Small molecule compound	MG-132 (proteasome inhibitor)	MG-132 leads to rapid accumulation of Cdc6. Effects of MG-132 are reversible with cyclohexamide (ab120093). Useful for Cdc6 degradation and localization studies24.	ab141003

Cdk4/6 and cyclin D1/2

Required for efficient cell proliferation and plays a role in tumorigenesis²⁵. Kinase activity of Cdk4-cyclin D complex is inhibited by increase in p21 levels²⁶. Cyclin D2 acts as a Cdk2 binding partner in absence of Cdk4 and Cdk6²⁷.

Type	Reagent name	Description	AbID
Antibody	Anti-Cdk4 antibody​	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: WB, IHC-P, Flow Cyt, ICC/IF	ab108357
	Anti-Cdk6 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: Flow Cyt, ICC/IF, IHC-P, WB	ab124821
	Anti-Cyclin D1 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu, Mo, Rt Applications: WB, IP, ICC/IF, IHC-P	ab134175
	Anti-Cyclin D2 antibody	Type: Rabbit monoclonal antibody Reactivity: Hu Applications: ICC/IF, IP, WB	ab207604
Kit	Cyclin D1 SimpleStep ELISA® kit	Quantitatively measure cyclin D1 protein in human cell and tissue extract samples. Reactivity: Hu Range: 187 pg/ml - 12000 pg/ml; Method: Colorimetric	ab214571
Small molecule compound	Palbociclib (Cdk4/6 inhibitor)	Highly potent Cdk4/6 inhibitor (IC50 = 11 nM and 16 nM for Cdk4/6)28.	ab218118
	Fascaplysin (Cdk4 inhibitor)	Potent, selective ATP-competitive CDK4 inhibitor (IC50 = 350 nM)29.	ab146177

Retinoblastoma protein (Rb)

Rb is inactivated following phosphorylated by Cdk2 and Cdk4/6. p21 inhibition of Cdk leads to dephosphorylation and activation of Rb. Rb forms a complex with E2F transcription factor and stalls cell cycle progression³⁰. p21 can negatively regulate Rb stalling of cell cycle via a feedback loop³¹.

Type	Reagent name	Description	AbID
Antibody	Anti-Rb binding protein 6 antibody	Type: Mouse polyclonal antibody Reactivity: Hu Applications: WB, ICC/IF	ab168511
	Anti-Rb binding protein 1 antibody	Type: Rabbit polyclonal antibody Reactivity: Hu Applications: ELISA, WB	ab25913
Small molecule compound	Silibinin (Rb activator)	Increases levels of unphosphorylated Rb (active) 4-fold with 70-90% decrease in phosphorylated Rb (inactive)32.	ab142948
	PD0332991 (Rb activator)	Clinically shown to activate Rb and promote tumor suppression33.	ab218118
	PAI-1 (Rb activator)	Plasminogen Activator Inhibitor (PAI-1) colocalizes with Rb and increases Rb activity34.	ab142349

MDM2 

A negative regulator of p21. MDM2 inhibition elevates p21 while its overexpression has the opposite effect. MDM2 binds p21 and directs it to proteasome-mediated degradation³⁵.

Type	Reagent name	Description	AbID
Antibody	Anti-MDM2 antibody	Type: Mouse monoclonal Reactivity: Hu, Mo Applications: Flow Cyt, ICC/IF, IHC-P, IP, WB	ab16895
Protein	Recombinant Human MDM2	Protein for use as a control in WB.	ab167941
Small molecule compound	Nutlin-3a (MDM2 inhibitor)	Potent p53-MDM2 binding inhibitor (IC50 = 90 nM)36. Causes activation of p21 at levels greater than etoposide (ab120227).	ab144428
	NSC 66811 (MDM2 inhibitor)	Potent, cell-permeable MDM2 inhibitor (Ki = 120 nM). Induces p21, p53 and MDM2 accumulation in human colon cancer cells37.	ab142190

p21 cell cycle analysis

Modulating p21 and its associated Cdk target proteins can cause DNA damage, replication stress and DNA accumulation. Studying DNA changes during cell cycle arrest will help better characterize cell cycle progression and the effect of target modulation.

Type	Reagent name	Description	AbID
Kit	Cell Cycle Assay Kit (Fluorometric)	Monitor cell cycle progression in G0/G1, S and G2/M phases using flow cytometry38. Ex/Em = 490 nm/520 nm	ab112116
Protein	Cell Cycle and Apoptosis WB Cocktail	Controls for WB of molecular markers for the G1/S and M phases of the cell cycle (pCdk/pHH3/Actin/PARP)	ab139417
Small molecule compound	BrdU	Cell proliferation reagents can be used for labelling DNA and studying DNA accumulation following modulation of p21 and other cell cycle proteins39. Detection antibodies for BrdU (ab6326), ldU (ab181664).	ab142567
	CldU		ab213715
	IdU		ab142581
	EdU	Thymidine analog and BrdU alternative that does not require antibodies or DNA denaturation40. EdU can be used to study DNA damage following p21 induction39.	ab146186

Click here for the cell proliferation guide

References

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13. Carlson, B. A., Dubay, M. M., Sausville, E. A., Brizuela, L. & Worland, P. J. Flavopiridol induces G1 arrest with inhibition of cyclin-dependent kinase (CDK) 2 and CDK4 in human breast carcinoma cells. Cancer Res. 56, 2973–8 (1996). Read more
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28. Fry, D. W. et al. Specific inhibition of cyclin-dependent kinase 4/6 by PD 0332991 and associated antitumor activity in human tumor xenografts. Mol. Cancer Ther. 3, 1427–38 (2004). Read more
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32. Tyagi, A., Agarwal, C. & Agarwal, R. Inhibition of retinoblastoma protein (Rb) phosphorylation at serine sites and an increase in Rb-E2F complex formation by silibinin in androgen-dependent human prostate carcinoma LNCaP cells: role in prostate cancer prevention. Mol. Cancer Ther. 1, 525–32 (2002). Read more
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34. Darnell, G. A. et al. Inhibition of retinoblastoma protein degradation by interaction with the serpin plasminogen activator inhibitor 2 via a novel consensus motif. Mol. Cell. Biol. 23, 6520–32 (2003). Read more
35. Zhang, Z. et al. MDM2 Is a Negative Regulator of p21WAF1/CIP1, Independent of p53. J. Biol. Chem. 279, 16000–16006 (2004). Read more
36. Vassilev, L. T. et al. In Vivo Activation of the p53 Pathway by Small-Molecule Antagonists of MDM2. Science (80-. ). 303, 844–848 (2004). Read more
37. Lu, Y. et al. Discovery of a nanomolar inhibitor of the human murine double minute 2 (MDM2)-p53 interaction through an integrated, virtual database screening strategy. J. Med. Chem. 49, 3759–3762 (2006).Read more
38. García-Castro, B. et al. Restoration of WNT4 inhibits cell growth in leukemia-derived cell lines. BMC Cancer 13, 557 (2013). Read more
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40. Zeng, C. B. et al. Evaluation of 5-ethynyl-2 ’-deoxyuridine staining as a sensitive and reliable method for studying cell proliferation in the adult nervous system. Brain Res. 1319, 21–32 (2010).Read more