pRb in the Differentiation of Normal and Neoplastic Cells.

This chapter deals with the role played by the retinoblastoma protein (pRb) in a variety of differentiation processes. After broadly reviewing the current knowledge on this issue, it points at two common themes. The first is the exclusive involvement of pRb in the final maturation stages of each lineage, so that the functional ablation of the protein produces relatively subtle differentiation defects. The second is that, at least in the cell types more thoroughly investigated, pRb exerts its pro-differentiation potential by enhancing the activities of transcription factors that are key regulators of tissue-specific differentiation. Finally, the hypothesis is put forward that pRb plays a role in the final differentiation stages of a much wider range of cell types than currently recognized. It is proposed that one reason for the well-know, poorly-understood, inverse relationship between differentiation and malignancy is the functional impairment of pRb and possibly its family members in the vast majority of human cancers. [ABSTRACT FROM AUTHOR]