Activates apoptosis. (Microbial infection) Involved in Hepatatis C virus (HCV) assembly and required for HCV entry into hepatocytes. Inhibited by DFFB. Interacts with DFFA and DFFB. (Microbial infection) Interacts (via N-terminus) with HCV non-structural protein 5A (via N-terminus); this interaction seems to regulate the association of HCV particles with ApoE. Highly expressed in liver and small intestine and, at lower levels, in colon, kidney and spleen.