Western blot was performed using Anti-C4BPA Polyclonal Antibody (Product # PA5-42001) and bands corresponding to 93kDa and 52kDa of C4BPA were observed in the reported high expressing models- Hep G2, Mouse Epididymis, Mouse Liver, Rat Epididymis and Rat Liver in comparison to DU 145, U-937, BeWO and Mouse Lung . Whole cell extracts (30 µg lysate) of Hep G2 (Lane 1), DU 145 (Lane 2), U-937 (Lane 3), BeWO (Lane 4), tissue extracts (30ug lysate) of Mouse Lungs (Lane 4), Mouse Epididymis (Lane 5), Mouse Liver (Lane 6), Rat Epididymis (Lane 7) and Rat Liver (Lane 8) were electrophoresed using NuPAGE™ 10% Bis-Tris Protein Gel (Product # NP0302BOX). Resolved proteins were then transferred onto a nitrocellulose membrane (Product # IB23001).The blot was probed with the antibody (0.75 µg/ml) and detected by ECL with Goat anti-Rabbit IgG (H+L), Superclonal™ secondary, HRP (Product # A27036, 1:4000 dilution). ECL was performed using Novex® ECL Kit (Product # WP20005). C4 protein, composed of alpha, beta and gamma chain, forms a heterotrimer of ~93 kDa alpha chains via disulphide linkage as detected by this antibody and a ~52 kDa protein corresponding to mouse and rat specific isoforms of C4BPA. It is also reported to be secreted by the epithelial cells surrounding the epididymis for sperm maturation in a region-specific, androgen dependent and species specific manner in addition to being synthesized in the liver.