Allograft Inflammatory Factor 1 (AIF1) contains two EF-hand domains and exists as a homodimer. AIF1 can be detected in T-lymphocytes and peripheral blood mononuclear cells. AIF1 functions as actin-binding protein that enhances membrane ruffling and RAC activation and can enhance the actin-bundling activity of LCP1. In addition, AIF1 plays a role in RAC signaling and in phagocytosis and may also in macrophage activation and function. AIF1 promotes the proliferation of vascular smooth muscle cells and of T-lymphocytes and plays a role in vascular inflammation.