MST2

MST2 (STK3) is a core Hippo pathway kinase that regulates organ size, self-renewal, tissue homeostasis, apoptosis, and tumor suppression through MST1/2-LATS1/2 control of YAP/TAZ activity[1][2]. Mechanistically, MST2 participates in MST1/2-dependent phosphorylation signaling to MOB1, LATS1/2, and YAP, linking cell contact, substrate stiffness, growth control, and stress-associated apoptosis[1][3]. In cancer models, MST2 contributes to apoptosis machinery in HER2+ breast cancer cells, while STK3 activation inhibits ESCC proliferation and migration through FOXO1-TP53INP1/P21 signaling[3][4]. Compared with related isoforms, MST2 differs functionally from MST1 because MST2 was essential for MST1/N activation and apoptosis induction, and differs from MST3 because MST3 regulates AMPK and YAP-Hippo signaling in renal fibrosis models[3][5]. For experimental applications, XMU-MP-1 is a reversible MST1/2 inhibitor that blocks MST1/2 kinase activity, activates YAP, and promotes liver and intestinal repair in acute and chronic injury models[6].