ATP binding cassette (ABC) transporter expression by ovarian cancer cell lines. ABCB3 (A), ABCB4 (B), ABCC2 (C) and ABCC3 (D). Relative gene expression was determined by calibration against OVCAR-3 cell expression and normalized to the house keeping gene β-actin using the 2-∆∆CT method. Data represents mean ± SEM from 3 independent experiments performed in triplicate. *, significantly different from OVCAR-3 cells (P < 0.05, One Way ANOVA & Tukey multiple comparison post hoc test).