This poster gives an overview of recent research into cytochrome P450 CYP1B1, which has previously been shown to present increased expression in several types of human cancer. This study specifically used immunohistochemistry to investigate the expression of CYP1B1 in a series of primary breast cancers. The majority of breast cancers showed positive immunoreactivity for CYP1B1 and this enzyme was specifically localised to tumour cells. This is likely to contribute to breast cancer cells' metabolism of oestradiol and also means that CYP1B1 provides a molecular target for anti-cancer drugs that are specifically activated by this form of P450