Fig. 4. Possible role of the MAPK and JAK/STAT pathways in the augmentation of ß-casein gene promoter activity by PhIP. Competent HC11 cells were treated with (+) or without (-) PhIP (100µM) and indicated concentrations of either the JAK2-selective inhibitor AG490 or the MEK-specific inhibitor PD98059. ß-Casein promoter activity was assayed after 48 h. A, effect of AG490 and/or PhIP on ß-casein promoter activity. B, effect of PD98059 and/or PhIP on ß-casein promoter activity. C and D, Western blot analysis of raf-1 and phospho-ERK levels in cells exposed to 100 µM PhIP (or DMSO control) for 48 h. In A and B, values are the means ± SE of four determinations.