Expression profile and electrophoretic mobility of R69W and A304V mutants. (A) Flow cytometry of MCP expression on CHO cell lines. Stable transfectants R69W and A304V express similar copy number of MCP/cell (approximately 100 000) compared with wild type. (B) Western blot of these same CHO cell lysates probed with a rabbit polyclonal Ab to MCP. R69W and A304V have similar M_r to wild type. Representative experiment of 3.