Coactivator of Warts (Wts) kinase in the Hippo/SWH (Sav/Wts/Hpo)signaling pathway, a signaling pathway that 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 Hippo (Hpo), in complex with its regulatory protein Salvador (Sav), phosphorylates and activates Warts (Wts) in complex with its regulatory protein Mats, which in turn phosphorylates and inactivates the Yorkie (Yki)oncoprotein. The Hippo/SWH signaling pathway inhibits the activity of the transcriptional complex formed by Scalloped (sd) and Yki and the target genes of this pathway include cyclin-E (cycE), diap1 and bantam. Mats is essential for early development and is required for proper chromosomal segregation in developing embryos. Interacts with and activates trc and wts. Colocalizes with wts and cyclin E at the centrosome. Ubiquitously expressed at low levels in developing tissues (at protein level). Phosphorylated by wts/mats kinase complex. Activated by phosphorylation by Hippo (Hpo) kinase which increases its affinity and its ability to activate Warts (Wts) kinase. Increased cell proliferation, defective apoptosis, and induction of tissue overgrowth. Belongs to the MOB1/phocein family.