All tags p21 Cdk-cylin complex and its effectors

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.

Cdk cannot phosphorylate downstream targets thereby leading to cell cycle arrest2



​​Cdk1 (Cdc2, p34Cdc2)

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.

TypeReagent nameDescriptionAbID
AntibodyAnti-CDK1 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: ICC/IF, Flow Cyt, WB, IP, IHC-P
Anti-CDK1 (phospho Y15) antibodyY15: Phosphorylated inhibitory residue of Cdk1 causing G1 block4.

Type: Rabbit polyclonal antibody
Reactivity: Hu, Mo, Rt
Applications: WB, ELISA
Anti-CDK1 (phospho T14) antibodyT14: Phosphorylated inhibitory residue of Cdk1 causing G1 block4.

Type: Rabbit polyclonal antibody
Reactivity: Hu, Mo, Rt
Applications: WB, ELISA
Anti-CDK1 (phospho T161) antibodyT161: Phosphorylated residue that stabilizes Cdk-cyclin B1 complex5.

Type: Rabbit polyclonal antibody
Reactivity: Hu, Mo, Rt
Applications: WB, ELISA
KitCDK1 SimpleStep® ELISA kit

Get fast, reproducible results in 90 minutes.

Reactivity: Hu
Range: 93.75 pg/ml-6000 pg/ml
Method: Colorimetric

molecule compound
(Cdk1 inhibitor)
Selective, reversible small molecule Cdk1 inhibitor (Ki = 35 nM Cdk1/cyclin B).ab141491
(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.

TypeReagent nameDescriptionAbID

Anti-Cyclin B1 antibodyValidated using a knockout cell line

Type: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, IHC-P, Flow Cyt, ICC, IP
Anti-Cyclin B1 (p S126) antibodyS126-phosphorylated cyclin B1 binds to T57-phosphorylated p21. Promotes kinase activation and G2M progression8.

Type: Rabbit monoclonal antibody
Reactivity: Hu
​Applications: IP, WB
Small molecule compoundPaclitaxel (Taxol)Cyclin B1 suppression increases taxol sensitivity and inhibits tumor growth9.ab120143
Leptomycin BInduces 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.

TypeReagent nameDescriptionAbID
AntibodyAnti-Cdk2 antibodyValidated using a knockout cell lineType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: ICC/IF, IP, WB, Flow Cyt, IHC-P
Anti-CDK2 (phospho Y15) antibodyY15: Inhibitory phosphorylation site by Wee1 kinase12.

Type: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: IHC-P, WB, IP
Anti-CDK2 (phospho T14) antibodyT14: Inhibitory phosphorylation site by Wee1 kinase12.

Type: Rabbit monoclonal antibody
Reactivity: Hu, Rt, ChHa
Applications: WB, IP, IHC-P, ICC
Anti-CDK2 (phospho T160) antibodyT160: Phosphorylation that stabilizes the Cdk2-cyclin complex12.

Type: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
​Applications: IHC-P, WB
Small molecule compoundFlavopiridol
(Cdk2 inhibitor)
Potent inhibitor Cdk2 kinase activity (IC50 = 100 nM at 400 μM ATP)13.ab141300
(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

TypeReagent nameDescriptionAbID
AntibodyAnti-Cyclin E1 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: IHC-P, WB
Small molecule compoundSorafenib
(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.

TypeReagent nameDescriptionAbID
AntibodyAnti-Cyclin A1/A2 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, IHC-P, IP
Anti-Ku70 antibodyKu70 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


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

TypeReagent nameDescriptionAbID
AntibodyAnti-Cdc25C antibodyValidated using a knockout cell lineType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, IHC-P, ICC/IF, Flow Cyt, IP
Small molecule compoundNSC 663284
(Cdc25 inhibitor)
Potent and selective inhibitor of Cdc25 (Ki = 89 nM for Cdc25C)19.ab144408
(Cdc25 activator)
Induces G2/M arrest and inhibits cell proliferation via Chk1 phosphorylation of Cdc25C20.ab145623
LysateCdc25C lysateCdc25C overexpression 293T lysate suitable for WB as a control.

Concentration: 100 µl at 1.7 mg/ml (1x sample buffer)


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

TypeReagent nameDescriptionAbID
AntibodyAnti-Cdc6 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, IHC-P, ICC
Anti-Cdc6 (phospho S54) antibodyPhosphorylation on S54 prevents Cdc6 from APC/C-dependent proteolysis22.

Type: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, ICC/IF
Anti-Cdc6 (phospho S106) antibodyCdk2-Cyclin E phosphorylation site required to induce G2 arrest23.

Type: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB
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
Small molecule compoundMG-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.

TypeReagent nameDescriptionAbID
AntibodyAnti-Cdk4 antibodyValidated using a knockout cell lineType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: WB, IHC-P, Flow Cyt, ICC/IF

Anti-Cdk6 antibodyValidated using a knockout cell line

Type: Rabbit monoclonal antibody
Reactivity: Hu
Applications: Flow Cyt, ICC/IF, IHC-P, WB
Anti-Cyclin D1 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu, Mo, Rt
Applications: WB, IP, ICC/IF, IHC-P
Anti-Cyclin D2 antibodyType: Rabbit monoclonal antibody
Reactivity: Hu
Applications: ICC/IF, IP, WB
KitCyclin 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

Small molecule compoundPalbociclib
(Cdk4/6 inhibitor)
Highly potent Cdk4/6 inhibitor (IC50 = 11 nM and 16 nM for Cdk4/6)28.ab218118
(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.

TypeReagent nameDescriptionAbID
AntibodyAnti-Rb binding protein 6 antibodyType: Mouse polyclonal antibody
Reactivity: Hu
Applications: WB, ICC/IF
Anti-Rb binding protein 1 antibodyType: Rabbit polyclonal antibody
Reactivity: Hu
Applications: ELISA, WB
Small molecule compoundSilibinin
(Rb activator)
Increases levels of unphosphorylated Rb (active) 4-fold with 70-90% decrease in phosphorylated Rb (inactive)32.ab142948
(Rb activator)
Clinically shown to activate Rb and promote tumor suppression33.ab218118
(Rb activator)
Plasminogen Activator Inhibitor (PAI-1) colocalizes with Rb and increases Rb activity34.ab142349


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.

TypeReagent nameDescriptionAbID
AntibodyAnti-MDM2 antibodyType: Mouse monoclonal
Reactivity: Hu, Mo
Applications: Flow Cyt, ICC/IF, IHC-P, IP, WB
ProteinRecombinant Human MDM2Protein for use as a control in WB.ab167941
Small molecule compoundNutlin-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.

TypeReagent nameDescriptionAbID
KitCell 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
ProteinCell Cycle and Apoptosis WB CocktailControls for WB of molecular markers for the G1/S and M phases of the cell cycle (pCdk/pHH3/Actin/PARP)ab139417
Small molecule compoundBrdUCell 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
EdUThymidine 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


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