This gene encodes a protein which binds to the SH3 domain of the Yes proto-oncogene product, a tyrosine kinase. This protein contains a WW domain, consisting of four conserved aromatic amino acids including two tryptophan residues. This conserved WW domain is found in various structural, regulatory and signaling molecules in various species, and may play a role in protein-protein interaction. Transcriptional regulator which can act both as a coactivator and a corepressor and is the critical 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. The core of this pathway is composed of a kinase cascade wherein STK3/MST2 and STK4/MST1, in complex with its regulatory protein SAV1, phosphorylates and activates LATS1/2 in complex with its regulatory protein MOB1, which in turn phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ. 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 suppresses F-actin polymerization. Plays a key role to control cell proliferation in response to cell contact.