CtIP, a multivalent adaptor connecting transcriptional regulation, checkpoint control and tumor suppression.

CtIP was originally characterized as an interacting protein for the transcriptional corepressor CtBP. In addition to transcriptional regulation, CtIP plays an important role in the DNA damage response and cell cycle checkpoint control. Recent evidence points to a viral factor-like S phase promoting activity of CtIP in counteracting Rb repression to facilitate E2F-directed transactivation during the G(1)/S transition. Genetic studies in mice revealed the haploid insufficiency of CtIP in suppressing tumorigenesis associated with shortened life span. Thus, CtIP emerges as a multivalent adaptor that connects cell cycle checkpoint control, transcriptional regulation and tumor suppression.