Western blot analysis of circulating apoA-IV. Serum samples were obtained at the conclusion of the 7-day experimental period, about 24 hours after the last intraperitoneal injection of rhA-IV. Serum samples were subjected to SDS-PAGE on 10% gels, transferred to nitrocellulose, then probed using an affinity-purified rabbit anti–rhA-IV antibody, followed by HRP-coupled goat anti-rabbit IgG antibody. (A) Effect of rhA-IV injection on serum apoA-IV in C57BL/6 mice from series I experiments. (B) Serum apoA-IV in an ApoA-IV–/– mouse with or without exogenous administration of rhA-IV, compared with serum apoA-IV in a WT littermate.