TRANSCRIPTIONAL REGULATION BY THE RETINOBLASTOMA TUMOR-SUPPRESSOR PROTEIN

The protein product of the retinoblastoma susceptibility gene (Rb) is a tumor suppressor implicated in controlling tumorigenesis in a subset of human cancers. Rb also functions to regulate cell differentiation, apoptosis, and senescence and is a target of important cell cycle reg ulatory proteins. Although the mechanism through which Rb mediates the se diverse biological effects on the cell is unclear, the ability of R b to regulate transcription is most likely important for its biologica l effects. Rb regulates transcription by interacting directly with spe cific upstream and basal transcription factors, resulting in either po sitive or negative regulation of expression of a subset of genes encod ing important cell cycle regulatory proteins. A description of the bio logical activites of Rb and the mechanisms through which Rb modulates transcription is presented.