Tumor suppressor genes in the cell cycle.

In the past year, two tumor suppressor genes, retinoblastoma and p53, have been established as important players in cell-cycle control, mediated by phosphorylation and by stage-specific transcription complexes. Evidence that they also participate in other transcription complexes is accumulating and searches are underway for the downstream genes under their regulation. Genes down-regulated in tumor cells are being screened by subtractive hybridization to bridge the gap between transcription factors and their targets.