Biological properties of the OC3 and OC3/P cell lines. A: morphology of two cell lines viewed by inverted light microscopy (original magnification, ×20 and × 40). B: OC3 and OC3/P cell growth curves. Cell viability was determined with the CCK-8 assay every 24 h, for 6 days. C: Basal levels of mdr1 mRNA analyzed by Q-PCR. Relative expression was calculated following normalization to GAPDH levels.