The ability of an anti-bPDI antibody (A) and an anti-human P5 antibody (B) to detect PDI family proteins was tested by Western-blot analysis. Lane 1, marker proteins; lane 2, hPDI; lane 3, hP5; lane 4, hPDIR; lane 5, bPDI; lane 6, yPDI. Approx. 5 μg of each protein was used.