ABCG2 expression is elevated in log-phase myeloma cells. (A) Flow cytometric data using an ABCG2 antibody (Chemicon) demonstrate that ABCG2-expressing 8226 cells have increased ABCG2 at log-phase density compared with log-phase H929 cells. (B-C) The FACScan data are confirmed by immunostaining for ABCG2 (B), and by QPCR and Western analyses (C). Densitometry analysis of the immunoblot shows a 4:1 ratio of log-plateau ABCG2 in 8226 cells, and a 2:1 ratio of log-plateau 8226MR ABCG2. Error bars represent the standard deviation for 3 separate experiments. Note, 8226 and 8226MR Western blots were exposed for different time intervals and do not reflect relative protein levels.