FHOD1 (formin homology 2 domain containing 1) is an actin-regulating protein that nucleates, bundles, and organizes actin filaments to form functional stress fibers 1. The protein contains a unique bipartite N-terminal structure with a GTPase-binding domain (GBD) and FH3 domain that enables activation by Rac and Ras GTPases through displacement of its C-terminal diaphanous autoregulatory domain (DAD) 2. Unlike other formins, FHOD1 exhibits strong F-actin bundling activity but relatively weak polymerization activity 3. FHOD1 uniquely associates with the nuclear envelope through high-affinity binding to nesprin-1G and nesprin-2G proteins, enabling nuclear mechanotransduction and positioning 3. The protein regulates diverse cellular processes including cell migration, adhesion maturation, and cytoskeletal organization 1. In disease contexts, FHOD1 plays complex roles in cancer, where it can regulate tumor immune microenvironments and impair immune cell function, contributing to immunosuppression 4. In gastric cancer, FHOD1 expression correlates with CD8+ T lymphocyte infiltration 5, while in atherosclerosis, it serves as a diagnostic biomarker associated with smooth muscle cell phenotypic switching 6. FHOD1's multifaceted functions make it a critical regulator of cytoskeletal dynamics and cellular mechanobiology.