Detection of Human Collagen XIII a1 by Western Blot. Western blot shows lysates of HUVEC human umbilical vein endothelial cells. PVDF Membrane was probed with 1ug/ml of Human Collagen XIII a1 Antigen Affinity purified Polyclonal Antibody followed by HRPconjugated AntiSheep IgG Secondary Antibody. Two specific bands were detected for Collagen XIII a1 at approximately 100 and 110kD (as indicated). This experiment was conducted under reducing conditions and using Immunoblot Buffer Group 8.