Upregulation of Egr-1 and oncogenes by primary bile acids. (A) Egr-1 and TGR-5 protein expression levels were measured in AGS and NCI-N87 cells using western blotting. CA and CDCA increased the Egr-1 expression but did not affect the TGR-5 expression in human gastric cancer cells. P-p42/44MAPK, AKT and p38MAPK protein expression levels were measured in (B) AGS and (C) NCI-N87 cells using western blotting. P-p42/44MAPK, AKT and p38MAPK protein expression levels were measured in (D) AGS and (E) NCI-N87 cells using quantitative reverse-transcription PCR. CDCA significantly increased (>2-fold) the phosphorylation of p42/44MAPK, AKT and p38MAPK in AGS and NCI-N87 cells. Fold change in protein expression was calculated by dividing the normalized signal intensity of the target band in the experimental sample by that of the target band in the control sample. *P<0.05, **P<0.01, and ***P<0.001. Egr-1, early growth response factor 1; TGR-5, G-protein coupled bile acid receptor 1; CA, cholic acid; CDCA, chenodeoxycholic acid; p-, phosphorylated; t-, total; TCA, taurocholic acid; GCDCA, glycochenodeoxycholic acid.