Background：

Stress-activated， pro-apoptotic kinase which， following caspase-cleavage， enters the nucleus and induces chromatin condensation followed by internucleosomal DNA fragmentation. Key component of the Hippo signaling pathway which 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. Phosphorylation of YAP1 by LATS2 inhibits its translocation into the nucleus to regulate cellular genes important for cell proliferation， cell death， and cell migration. STK3/MST2 and STK4/MST1 are required to repress proliferation of mature hepatocytes， to prevent activation of facultative adult liver stem cells (oval cells)， and to inhibit tumor formation (By