CAP1 (cyclase associated actin cytoskeleton regulatory protein 1) is a multifunctional protein that regulates actin cytoskeleton dynamics and cellular signaling pathways. CAP1 directly controls actin filament organization and facilitates cytoskeletal rearrangement, driving cell migration and morphological processes 1. Beyond its cytoskeletal functions, CAP1 serves as a critical signaling mediator in multiple pathways. In platelets, CAP1 acts as a downstream interacting protein of nuclear receptor NR4A1, regulating cAMP levels and VASP phosphorylation to modulate platelet activation and thrombosis 2. CAP1 also functions as a key inflammatory mediator, serving as the main binding partner for PCSK9 and being essential for PCSK9-induced inflammatory responses, including cytokine production and oxidized LDL uptake 3. The resistin-CAP1 pathway has emerged as an important immunological mechanism, with CAP1+ classical monocytes showing elevated NF-κB activity in periodontal disease and diabetes 4, and mediating T cell-mediated liver allograft rejection 5. In cancer, CAP1 exhibits context-dependent roles, promoting cell proliferation through ERK regulation while influencing invasiveness through FAK signaling 16. CAP1 overexpression correlates with poor prognosis in epithelial ovarian cancer and enhanced proliferation 6.