The mammalian homologues of Drosophila Hippo (Hpo) are called MST1 kinase and MST2 kinase. Close to the cytoplasmic membrane, MST1/2 forms an active complex with WW repeat scaffolding protein WW45 (or Salvador in Drosophila). MST/WW45 complex then phosphorylates nuclear DBF-2-related kinase LATS1/2 (or Wts in Drosophila) with the help of another tumor suppressor Merlin/NF2, which is required for the recruitment of LATS1/2 to the cytoplasmic membrane. LATS in turn interacts with MOB to phosphorylate transcriptional coactivators YAP and TAZ (or Yorkie in Drosophila), causing inactivation excluion from the nucleus, and downregulation of genes important for cell cycle progressive, proliferation and organ growth.