Retinoblastoma-associated protein (Rb) is a key regulator of entry into cell division that acts as a tumor suppressor. Rb is directly involved in the heterochromatin formation by maintaining overall chromatin structure and, in particular, that of constitutive heterochromatin by stabilizing histone methylation. Defects in Rb are a cause of retinoblastoma, bladder cancer and osteogenic sarcoma.The synthetic peptide used to raise the antibody Cat. No. 200149 is selected from a sequence within the C-term region of human Rb. For blocking experiments, a 10 to 100 fold molar excess to antibody is recommended.