Detection of proteins with anti-EpoR antibodies. M-20, C-20, and 07-311 all detected 59-kDa proteins. C-20 detected a 66-kDa protein, whereas 07-311 detected an approximately 70-kDa protein. Protein extracts were prepared from COS-7 cells expressing FLAG-EpoR, UT-7/Epo cells (50 000 cells/lane), and Caki-2 cells (60 000 cells/lane). Proteins were resolved on a 7% gel and subjected to Western immunoblotting using the antibodies C-20 (0.132 ug/mL), 07-311 (0.1 μg/mL), or M-20 (0.2 μg/mL), as described previously.¹  Positions of the molecular weight markers are illustrated on the left (kDa).