FIGURE 6.

Abcb6 deficiency attenuates P450 expression in human hepatoma Huh7 and Hep3B cells. a and c, expression of CYP1A2, CYP2B6, and CYP3A4 but not CYP2E1 mRNA is repressed in ABCB6 knockdown Huh7 (a) and Hep3B (c) cells (bottom panels in a and c shows Abcb6 protein expression in knockdown cells). b and d, loss of endogenous ABCB6 expression does not affect heme levels in Huh7 (b) and Hep3B (d) cells. The data are presented as means ± S.E. from three independent measurements. *, significantly different from ABCB6 scrambled shRNA cells; p < 0.01. Heme levels were measured by HPLC as described under “Experimental Procedures.” mRNA expression was determined by real time RT-PCR.