CAVIN4 is a muscle-specific caveolar protein that regulates caveolae organization and cardiac function. Unlike other cavin family members, CAVIN4 modulates caveolae morphology in cardiomyocytes without being essential for caveolar formation itself 1. CAVIN4 facilitates recruitment of MAPK1/3 to caveolae and regulates alpha-1 adrenergic receptor-induced hypertrophic responses through MAPK1/3 activation, while also stabilizing caveolin-3 membrane localization [UniProt]. In skeletal muscle, CAVIN4 (also called Murc) is critical for proper T-tubule development and function, with loss-of-function mutations causing muscle fibrosis and impaired swimming capacity in zebrafish models 2. CAVIN4 activates RHOA and NPPA transcription via Rho/ROCK signaling, promoting myofibrillar organization [UniProt]. Clinically, CAVIN4 dysfunction is implicated in rippling muscle disease (RMD), where anti-cavin-4 antibodies serve as serological markers for immune-mediated RMD (iRMD), characterized by mosaic caveolin-3 and cavin-4 expression patterns 3. Notably, low CAVIN4 expression correlates with poor survival outcomes in leukemia, suggesting potential biomarker utility 4. CAVIN4 thus represents a critical regulator of muscle-specific mechanotransduction and cardiomyocyte signaling with relevance to both muscle disorders and hematologic malignancies.