ACAP1 is an ADP-ribosylation factor 6 (ARF6) GTPase-activating protein that regulates membrane trafficking and cell migration 1. Structurally, ACAP1 contains coiled-coil, ankyrin repeat, and pleckstrin homology (PH) domains, along with a BAR domain critical for detecting membrane curvature 2. Its primary function involves mediating clathrin-dependent protein export from recycling endosomes to the trans-Golgi network and cell surface, including regulated integrin β1 trafficking essential for cell migration 34. ACAP1 activity is regulated through Akt-mediated phosphorylation, which relieves autoinhibition and enhances cargo binding 4. The protein functions within distinct endosomal compartments separate from other ARF6 GAPs like ARAP2, defining specialized trafficking pathways 3. ACAP1 activity is modulated by GULP, which sequesters ACAP1 to enhance Arf6-GTP levels and promote cell migration 5. Clinically, ACAP1 dysregulation associates with multiple diseases: elevated ACAP1 expression predicts poor ovarian cancer prognosis and correlates with immune infiltration and cancer stemness markers 1. In systemic lupus erythematosus, SLE risk alleles decrease ACAP1 expression in immune cells 6. In cholangiocarcinoma, ACAP1 mediates FGFR2-PTPN9 interaction, influencing response to pemigatinib therapy 7.