Fig. 1.

Expression of P-gp, Mrp1, and BCRP in three pairs of cell lines as determined by Western blot analysis. The three pairs are (listed as parental and resistant, respectively) as follows: MCF-7 and MCF-7/VP16 (ABCC1); KB-3-1 and KB-8-5-11 (ABCB1); and H460 and H460/MX20 (ABCG2). A protein ladder was loaded with each Western blot to mark the bands for Mrp1 (190 kDa), P-gp (160 kDa), BCRP (70 kDa), and GAPDH (40 kDa). Cell lysates were probed for GAPDH as a control for the amount of protein loaded. A nonspecific band appears in all the lanes when probed against BCRP.