Fig. 2. The Hippo kinase cassette. A schematic of the physical associations and the kinase-substrate relationships among proteins in the Hippo (Hpo) kinase cassette in (A) Drosophila and (B) mammals. Colored arrows identify proteins phosphorylated by Hpo/Mst (blue) and Warts/Lats (green). Hpo and Mst autophosphorylate and then phosphorylate Sav/WW45, Warts/Lats and Mats/Mob. The phosphorylation of Warts by Hpo is facilitated by Sav, which interacts with both proteins. Warts autophosphorylates and phosphorylates downstream effectors, including Yki/Yap, Taz and presumably other substrates (?). Abbreviations: Hpo, Hippo; Mats, Mob-as-tumor suppressor; Sav, Salvador; Taz, transcriptional co-activator with PDZ-binding motif; Yap, Yes-associated protein; Yki, Yorkie.