MST1 and osteosarcoma: ROCK2 overexpression resulted in increased levels of the ROCK2-Salvador homology 1 (SAV1) complex and decreased levels of the mammalian STE20-like protein kinase 1 (MST1)-SAV1 complex, thereby inhibiting activation of the Hippo pathway, which in turn led to osteosarcoma MPPa-PDT resistance by regulating cellular autophagy.