The tumor suppressor RASSF1A is a novel effector of small G protein Rap1A

Rap1A is a small G protein implicated in a spectrum of biological processes such as cell proliferation,adhesion,differentiation,and embryogenesis.The downstream effectors through which Rap1A mediates its diverse effects are largely unknown.Here we show that Rap1A,but not the related small G proteins Rap2 or Ras,binds the tumor suppressor Ras association domain family 1A(RASSF1A)in a manner that is regulated by phosphorylation of RASSF1A.Interaction with Rap1A is shown to influence the effect of RASSF1A on microtubule behavior.