FRMD3 (FERM domain containing 3) is a tumor suppressor protein that plays critical roles in cellular structure regulation and disease pathogenesis. The protein functions as a cytoskeletal regulator through protein-protein interactions, particularly with components of cell-cell junctions and cytoskeletal elements 1. FRMD3 acts as a tumor suppressor in breast cancer by promoting ubiquitination-mediated degradation of vimentin through interaction with UBE3A, leading to downregulation of focal adhesion complex proteins and subsequent inhibition of cell proliferation, migration, and invasion 2. In mammary epithelial cells, FRMD3 controls cell fate determination by modulating the Notch signaling pathway through regulation of Disheveled-2 degradation and nuclear localization 3. The protein is clinically significant in multiple disease contexts: reduced FRMD3 expression is associated with chr9 kidney disease severity and progression, with knockdown resulting in increased apoptotic activity and E-cadherin dysregulation in tubule epithelial cells 1. Genetic variants near FRMD3 are associated with diabetic kidney disease risk 45. Low FRMD3 expression correlates with poor outcomes in breast cancer patients and contributes to immune evasion by creating 'cold tumors' resistant to checkpoint inhibitors 26.