Effect of retinoic acid on TGF-β2 mRNA quantified by real-time RT-PCR in human pancreatic cancer cells. CAPAN-2 (top panel) and Hs766T cells (bottom panel) were treated with 0.1–10 μM retinoic acid for 18 hours. Retinoic acid caused a significant concentration-dependent increase in the TGF-β2 mRNA expression in these cells. Values were normalized to levels of mRNA for GAPDH, which was also used as a loading control. One way ANOVA: Capan-2: F(3,11) = 15.0, P = 0.0012; HS766T: F(3,11) = 4.72, P = 0.034. Data are expressed as fold-change from untreated cells, bars represent means ± SEM. Significance of individual comparisons after Dunnett's multiple comparison test is indicated by * = P < 0.05, ** = P < 0.01.