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. Acts by mediating gene expression of YAP1 and WWTR1/TAZ, thereby regulating cell proliferation, migration and epithelial mesenchymal transition (EMT) induction. Binds specifically and cooperatively to the SPH and GT-IIC 'enhansons' (5'-GTGGAATGT-3') and activates transcription in vivo in a cell-specific manner. The activation function appears to be mediated by a limiting cell-specific transcriptional intermediary factor (TIF). Involved in cardiac development. Binds to the M-CAT motif (By similarity). Interacts with YAP1 and WWTR1/TAZ. In developing skeletal muscle and myocardium, in mitotic neuroblasts both in the brain and spinal cord. At later stages of embryogenesis expressed in several developing structures such as the olfactory system, the intestine, and the kidney. It is uncertain whether Met-1 or Met-16 is the initiator. Unusual initiator. The initiator methionine is coded by a non-canonical ATT isoleucine codon. Unusual initiator. The initiator methionine is coded by a non-canonical ATT isoleucine codon. Unusual initiator. The initiator methionine is coded by a non-canonical ATT isoleucine codon.