SAV1 (salvador family WW domain containing protein 1) functions as a critical regulatory component of the Hippo signaling pathway, serving as a tumor suppressor that controls organ size and prevents tumorigenesis. SAV1 forms complexes with MST1/MST2 kinases to activate downstream LATS1/2 kinases, which subsequently phosphorylate and inactivate YAP1/TAZ oncoproteins, preventing their nuclear translocation and proliferation-promoting transcriptional activity 12. The protein undergoes post-translational regulation through various mechanisms, including sulfation by SLC35B2 under oxidative stress conditions, which disrupts SAV1-MST1 complex formation and inactivates Hippo signaling in hepatocellular carcinoma 3. SAV1 functions within phase-separated biomolecular condensates that facilitate Hippo pathway activation 4. Clinically, SAV1 acts as a tumor suppressor across multiple cancer types. SAV1 mutations occur in intrahepatic cholangiocarcinoma and are associated with poor patient outcomes 5. In non-small cell lung cancer, smoking-induced SAV1 promoter hypermethylation disrupts YAP negative feedback regulation, promoting malignant progression 6. Additionally, SAV1 expression is decreased in gastric cancer tissues and correlates with better patient survival, with KDM2B transcriptionally regulating SAV1 levels 7. These findings establish SAV1 as a key tumor suppressor with significant therapeutic potential.