FCHSD2 is an F-BAR adapter protein that orchestrates clathrin-mediated endocytosis and membrane trafficking through coordinated actin polymerization. Its primary function is to facilitate the internalization of cell surface receptors, including integrin ITGB1 and transferrin receptor, by promoting progression from U-shaped to omega-shaped clathrin-coated pits 1. FCHSD2 is recruited to clathrin-coated pits by the scaffold protein intersectin 1 and to endosomal membranes by MICAL-L1 2. Once membrane-bound to regions enriched in phosphatidylinositol 3,4-bisphosphate or 3,4,5-trisphosphate, FCHSD2 activates Arp2/3-mediated branched actin polymerization through direct interaction with WASP/N-WASP, driving both pit maturation and endosomal fission 1, 2. In hair cells, FCHSD2 localizes to stereocilia and interacts with deafness-related protein PDZD7, linking cytoskeletal dynamics to stereociliary development 3, 4. Clinically, FCHSD2 regulates receptor tyrosine kinase trafficking in cancer cells; its loss promotes lysosomal degradation of EGFR and MET, triggering compensatory ERK1/2 signaling associated with worse prognosis in non-small-cell lung cancer 5.