CYP2S1 and breast cancer: A previous study examined the expression profile of 21 CYP genes in breast cancer cells using a tissue microarray containing 170 breast cancers and reported that the highest percentage of strong immunopositivity was seen for CYP4X1, CYP2S1 and CYP2U1, while CYP2J and CYP3A43 frequently displayed no immunoreactivity17.