ELISA overestimates dimeric erythropoietin by 5 times.

(Lane 1) 3 U, (lane 2) 2 U, and (lane 3) 1 U human HA-tagged dimeric erythropoietin and 0.6 U (lane 4), 0.4 U (lane 5), and 0.2 U (lane 6) human HA-tagged monomeric erythropoietin (as measured by R&D ELISA) were run on SDS-PAGE, blotted, and detected with an anti-HA antibody.