MAPK inhibitors reduced EPA-induced Cx43 expression. (A) The B16F10 cells were treated with EPA (0-100 μM) for 24h. The cells were lysed and protein expression of ERK, P38, JNK, P-ERK, P-P38, and P-JNK was examined. (B) After treatment of cells with inhibitor for p38 (SB203580) and JNK (SP600125) for 1h, The B16F10 cells were treated with EPA (100 μM) for 24h. The cells were lysed and protein expression of Cx43, P-P38, P-P38, JNK and p-JNK was examined. (C) EPA induced Cx43 transcriptional activity in B16F10 cells. The B16F10 cells transfected with luciferase gene under the control of Cx43 promoter were treated with EPA (0-100 μM) for 24 h. The transcriptional activity of Cx43 was determined by the luciferase reporter assay and is expressed as the fold of the relative luciferase activity relative to that in the control tumor cells. (n = 4, data are mean± SD. * P < 0.05, ** P < 0.01).