Fig. 8

a and b Resazurin Conversion Assay and subsequent Crystal Violet staining with Caco-2 cells grown on filter inserts. Protocol #7 describes the steps of the assays. Caco-2 cells were either left untreated (negative control) or were treated for 48 h with GW3965 (LXR agonist, 10 μM), T0901317 (LXR agonist, 10 μM), bexarotene (RXR agonist, 5 μM), digitonin (positive control, 50 μg/ml) or the vehicle control (DMSO 0.1%). Cells were then incubated with a dilution of resazurin in serum-free DMEM (10 μg/ml) for 2 h. Hereafter, fluorescence emission was measured in the apical medium (a). The inserts were then incubated with crystal violet solution for 10 min. After washing steps and drying overnight, crystal violet was solubilized using sodium citrate:ethanol and the OD was measured at 595 nm (b). Bar graphs represent mean ± SD from three independent experiments. ns not significant, *P < 0.05, ***P < 0.001 versus untreated (determined by paired t-test)