Role of the retinoblastoma protein family, pRB, p107 and p130 in the negative control of cell growth

The retinoblastoma family of proteins, also known as pocket proteins, inclu des the product of the retinoblastoma susceptibility gene and the functiona lly and structurally related proteins p107 and p130, Pocket proteins contro l growth processes in many cell types, and this has been linked to the abil ity of pocket proteins to interact with a multitude of cellular proteins th at regulate gene expression at various levels. By regulating gene expressio n, pocket proteins control cell cycle progression, cell cycle entry and exi t, cell differentiation and apoptosis, This review will focus on the mechan isms of regulation of pocket proteins and how modulation of pocket protein levels and phosphorylation status regulate association with their cellular targets. The coordinated regulation of pocket proteins provides the cells w ith a competence mechanism for passage through certain cell growth and diff erentiation transitions.