Protein salvador homolog 1 (SAV1)

Regulator of STK3/MST2 and STK4/MST1 at 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 then phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ.

Phosphorylation of YAP1 by LATS1/2 inhibits its translocation to the nucleus to regulate cellular genes important for cell proliferation, cell death, and cell migration. SAV1 is needed for STK3/MST2 and STK4/MST1 activation and promotes cell-cycle exit and terminal differentiation in developing epithelial tissues.