Transcriptional coactivator YAP1 (YAP1)

Transcriptional regulator which can act both as a coactivator and a corepressor and is the crucial downstream regulatory target in the Hippo signaling pathway that plays a pivotal role in organ size control and tumor suppression by restricting proliferation and promoting apoptosis (PubMed:17974916, PubMed:18280240, PubMed:18579750, PubMed:21364637). The core of this pathway is made up of a kinase cascade wherein STK3/MST2 and STK4/MST1, in complex with its own regulatory protein SAV1, phosphorylates and activates LATS1/2 in complex with its own regulatory protein MOB1, which then phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ (PubMed:18158288).

Plays a key role in tissue tension and 3D tissue shape by regulating cortical actomyosin network formation. Acts via ARHGAP18, a Rho GTPase activating protein that inhibits F-actin polymerization (PubMed:25778702).