Two-dimensional gel electrophoresis of human serum EPO.

IEF was carried out by using IPG strips with a pH gradient of 3 to 6. SDS-PAGE was performed in 12% gels followed by immunoblotting. Samples were detected with a biotinylated monoclonal antibody against hEPO using horseradish peroxidase–labeled streptavidin and a chemiluminescent substrate. (A) Human serum EPO (65 ng). (B) Epoetin alfa (50 ng). (C) Epoetin beta (50 ng).