SAV1 also known as WW45, WWP4 is a crucial protein involved in the regulation of the Hippo signaling pathway, which plays a significant role in controlling cell growth and apoptosis. SAV1 features one SARAH domain and two WW domains, with the SARAH domain facilitating protein-protein interactions essential for cell cycle regulation. Notably, SAV1 can form homodimers and acts as a scaffold protein, enabling the binding of Krs-2, a key regulator that restricts cell proliferation and promotes apoptosis. This interaction is vital for the nuclear translocation and activation of Krs-2, which subsequently leads to the phosphorylation of major tumor suppressors LATS1 and kpm. Proper functioning of SAV1 is critical, as defects in the Hippo pathway have been linked to tumorigenesis, indicating that dysfunctional SAV1 may contribute to the development of various cancers.