TWF1 (twinfilin actin binding protein 1) is an actin-binding protein that regulates cytoskeletal dynamics through multiple mechanisms. Functionally, TWF1 inhibits actin polymerization by sequestering G-actin and caps barbed ends of actin filaments, thereby controlling actin turnover and cellular motility 1. TWF1 phosphorylation at tyrosine 309 by Src kinase is essential for reelin signaling, which regulates actin remodeling and dendritic spine development; phospho-resistant mutants exhibit reduced spine density and cognitive deficits 2. Beyond developmental processes, TWF1 plays critical roles in cancer progression. In lung adenocarcinoma, TWF1 overexpression promotes migration, invasion, and autophagy through cAMP pathway suppression 3. Similarly, in hepatocellular carcinoma, TWF1 contributes to drug resistance and metastasis; miR-142-3p-mediated TWF1 suppression enhances tyrosine kinase inhibitor sensitivity by inhibiting autophagy 4. In renal cell carcinoma, miR-30a/c-5p targets TWF1 to suppress epithelial-mesenchymal transition and metastatic potential 5. TWF1 also serves as a pancreatic cancer biomarker; elevated expression in cyst fluid predicts malignancy and associates with poor prognosis 6. Additionally, TWF1 expression increases with aging and biliary injury, mediating cholangiocyte adaptation and senescence responses 7. These findings establish TWF1 as a multifunctional regulator of actin dynamics with broad implications for development, aging, and cancer pathobiology.