Fig. 1. Effect of PhIP on ß-casein promoter activity and gene expression in HC11 cells cultured with lactogenic hormones, DIP. Competent HC11-Lux cells were treated with PhIP in DM. A, concentration-dependent induction of luciferase activity in HC11-Lux cells treated with various concentrations of PhIP. B, induction of ß-casein promoter activity observed at various times after addition of 100 µM PhIP. In both A and B, the expression observed in the presence of PhIP in DM was compared with the expression observed in DM only. C, Northern blot analysis of ß-casein gene expression at various times after treatment with PhIP (100 µM) or in control (C) cells incubated in DM only. D, ethidium bromide-stained gel used for Northern blotting in panel C indicates equal loading of RNA in each lane. The ß-casein promoter activity was analyzed using the luciferase assay.