• Nature
  • Source
    Escherichia coli
  • Amino Acid Sequence
    • Species
    • Amino acids
      773 to 928
    • Tags
      GST tag N-Terminus


Our Abpromise guarantee covers the use of ab56270 in the following tested applications.

The application notes include recommended starting dilutions; optimal dilutions/concentrations should be determined by the end user.

  • Applications

    Functional Studies


  • Form
  • Additional notes

    ab56270 (Human Rb protein fragment) can be utilized as a substrate for the following active protein Kinases:


    ab55695 (Human Cdk4 + Cyclin D1 full length protein)
    ab84557 (Active human CDK6 + CCND3 full length protein)
    ab84559 (Active human CDK6 + CCND1 full length protein)

    ab85646 (Active human CDK4 + CCND3 full length protein)

    ab177576 (Active human PFTK1 (CDK14)/CyclinY full length protein)

    ab177586 (Active human PCTAIRE1 protein fragment)


  • Concentration information loading...

Preparation and Storage

  • Stability and Storage

    Shipped on dry ice. Upon delivery aliquot and store at -80ºC. Avoid freeze / thaw cycles.

    pH: 7.50
    Constituents: 0.00174% PMSF, 0.00385% DTT, 0.79% Tris HCl, 25% Glycerol, 0.87% Sodium chloride

General Info

  • Alternative names
    • Exon 17 tumor GOS561 substitution mutation causes premature stop
    • GOS563 exon 17 substitution mutation causes premature stop
    • OSRC
    • Osteosarcoma
    • p105-Rb
    • P105RB
    • PP105
    • pp110
    • PPP1R130
    • pRb
    • Prepro retinoblastoma associated protein
    • Protein phosphatase 1 regulatory subunit 130
    • Rb
    • RB transcriptional corepressor 1
    • RB_HUMAN
    • RB1
    • RB1 gene
    • Retinoblastoma 1
    • Retinoblastoma suspectibility protein
    • Retinoblastoma-associated protein
    see all
  • Function
    Key regulator of entry into cell division that acts as a tumor suppressor. Promotes G0-G1 transition when phosphorylated by CDK3/cyclin-C. Acts as a transcription repressor of E2F1 target genes. The underphosphorylated, active form of RB1 interacts with E2F1 and represses its transcription activity, leading to cell cycle arrest. Directly involved in heterochromatin formation by maintaining overall chromatin structure and, in particular, that of constitutive heterochromatin by stabilizing histone methylation. Recruits and targets histone methyltransferases SUV39H1, KMT5B and KMT5C, leading to epigenetic transcriptional repression. Controls histone H4 'Lys-20' trimethylation. Inhibits the intrinsic kinase activity of TAF1. Mediates transcriptional repression by SMARCA4/BRG1 by recruiting a histone deacetylase (HDAC) complex to the c-FOS promoter. In resting neurons, transcription of the c-FOS promoter is inhibited by BRG1-dependent recruitment of a phospho-RB1-HDAC1 repressor complex. Upon calcium influx, RB1 is dephosphorylated by calcineurin, which leads to release of the repressor complex (By similarity). In case of viral infections, interactions with SV40 large T antigen, HPV E7 protein or adenovirus E1A protein induce the disassembly of RB1-E2F1 complex thereby disrupting RB1's activity.
  • Tissue specificity
    Expressed in the retina.
  • Involvement in disease
    Childhood cancer retinoblastoma
    Bladder cancer
    Osteogenic sarcoma
  • Sequence similarities
    Belongs to the retinoblastoma protein (RB) family.
  • Domain
    The Pocket domain binds to the threonine-phosphorylated domain C, thereby preventing interaction with heterodimeric E2F/DP transcription factor complexes.
  • Post-translational
    Phosphorylated by CDK6 and CDK4, and subsequently by CDK2 at Ser-567 in G1, thereby releasing E2F1 which is then able to activate cell growth. Dephosphorylated at the late M phase. SV40 large T antigen, HPV E7 and adenovirus E1A bind to the underphosphorylated, active form of pRb. Phosphorylation at Thr-821 and Thr-826 promotes interaction between the C-terminal domain C and the Pocket domain, and thereby inhibits interactions with heterodimeric E2F/DP transcription factor complexes. Dephosphorylated at Ser-795 by calcineruin upon calcium stimulation. CDK3/cyclin-C-mediated phosphorylation at Ser-807 and Ser-811 is required for G0-G1 transition. Phosphorylated by CDK1 and CDK2 upon TGFB1-mediated apoptosis.
    N-terminus is methylated by METTL11A/NTM1 (By similarity). Monomethylation at Lys-810 by SMYD2 enhances phosphorylation at Ser-807 and Ser-811, and promotes cell cycle progression. Monomethylation at Lys-860 by SMYD2 promotes interaction with L3MBTL1.
    Acetylation at Lys-873 and Lys-874 regulates subcellular localization, at least during keratinocytes differentiation.
  • Cellular localization
  • Information by UniProt


  • ab56270 on SDS-PAGE.


This product has been referenced in:
  • Xue Y  et al. CDK4/6 inhibitors target SMARCA4-determined cyclin D1 deficiency in hypercalcemic small cell carcinoma of the ovary. Nat Commun 10:558 (2019). Read more (PubMed: 30718512) »
  • Meziane el K  et al. Knockdown of Fbxo7 reveals its regulatory role in proliferation and differentiation of haematopoietic precursor cells. J Cell Sci 124:2175-86 (2011). Blocking . Read more (PubMed: 21652635) »
See all 2 Publications for this product

Customer reviews and Q&As


Thank you for calling Abcam yesterday.

The protein comes, ab56270 is GST-tagged. Although we have not done any in-house activity assays with this particular protein, it should be suitable to be used as a substrate for activity assays.

Since we have not tested this protein in an activity assay, you could take advantage of our 100% Abreview Testing Discount program, details of which can be found in the link below:


If you would like to take advantage of the discount program, or if there is anything else I can help you with, please let me know.

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