The retinoblastoma protein (pRb) is a crucial tumor suppressor protein that plays a significant role in regulating the cell cycle. It is named after the rare childhood eye cancer, retinoblastoma, where mutations in the gene encoding this protein (RB1 gene) were first identified. By controlling the transition from the G1 to the S phase of the cell cycle, pRb ensures that cells only divide when they are supposed to.
