Expression of estrogen metabolism enzymes in MCF10A series and MCF7 cell lines. TaqMan Gene Expression assays were used to determine the relative levels of STS, SULT1A1, SULT2B1, SULT2A1 (a), 17βHSD1, 17βHSD2 (b), CYP19, CYP1B1, and COMT (c) mRNA in MCF10A series cell lines and in MCF7 cells. The mRNA levels are expressed relative to their respective levels in MCF10A cells, MCF7 cells or a human RNA reference pool (HRP). All values represent the mean ± SEM of three independent cell culture experiments. For all transcripts except 17βHSD2 and CYP1B1: Groups labeled with different letters are significantly different from each other (P <0.05). For 17βHSD2 and CYP1B1: *** Significantly different from all other groups, P < 0.001. When the group labeled with *** was omitted from the analyses, groups labeled with different letters are significantly different from each other (P < 0.05). For STS and COMT, no significant differences among groups were detected. For SULT2A1 and CYP19, mRNA levels were undetected in all cell lines