Isolithocholic and cholanic acids do not affect EGF receptor activity. PC3 cells were pretreated for 20 minutes with 100 μM lithocholic, isolithocholic or cholanic acid, 10 μM gefitinib, or 1% DMSO as a control, and stimulated for 20 minutes with 30 ng/ml EGF. Phospho-EGF receptor levels are relative to the EGF+DMSO condition. Data are the means of at least three independent experiments ± standard error. **, p<0,01 for the comparison to EGF+DMSO by one-way ANOVA followed by Tukey's multiple comparison test.