The RB Family of Cell Cycle Regulatory Factors

The intense investigation of the retinoblastoma "tumor suppressor family" members, pRb, pRb2/p130, and p107, has revealed impressive mechanisms evolved to safeguard development and homeostasis in higher eukaryotes. Members of the retinoblastoma family are involved in implementing and controlling three major aspects of cellular life: (1) proliferative growth, (2) differentiation, and (3) apoptosis. The activities of these proteins are highly regulated, enabling them to precisely establish control. The pRb protein is well understood in its regulatory abilities and is considered a classical tumor suppressor. The role of pRb2/p130 protein in growth suppression and its potential as a tumor suppressor have been established during the last few years. The p107 protein, structurally and functionally similar to, but yet distinctive from, pRb2/p130, is characterized at a more rudimentary level. In this report, we review the latest data on the retinoblastoma protein family and its web of regulatory mechanisms.