Transcription factor which plays a key role in the Hippo signaling pathway, a pathway involved 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 MST1/MST2, in complex with its regulatory protein SAV1, phosphorylates and activates LATS1/2 in complex with its regulatory protein MOB1, which in turn phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ (By similarity). High levels in cardiac muscle, low in skeletal muscle. Intermediate levels in gizzard and lung, low levels in kidney. Unusual initiator. The initiator methionine is coded by a non-canonical ATA isoleucine codon. Unusual initiator. The initiator methionine is coded by a non-canonical ATA isoleucine codon.