WWTR1 It is a transcriptional coactivator which acts as a downstream regulatory target in the Hippo 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 MST1/MST2, in complex with its regulatory protein SAV1, phosphorylates and activates LATS1/LATS2 in complex with its regulatory protein MOB1, which in turn phosphorylates and inactivates YAP1 oncoprotein and WWTR1/TAZ. WWTR1 enhances PAX8 and NKX2-1/TTF1-dependent gene activation. Regulates the nuclear accumulation of SMADs and has a key role in coupling them to the transcriptional machinery such as the mediator complex.
Using the human SHSY5Y cell line as a model of neuronal differentiation, human FAT1 was shown to regulate the nucleocytoplasmic relocation of WWTR1/TAZ and enhanced transcription of the Hippo target gene CTGF. The same study also showed FAT1 was able to regulate TGF-beta signalling 
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