CYP1A1 and CYP1B1 are not expressed in any significant quantity in the liver. Therefore, they would
not be expected to contribute to the overall systemic metabolism of estrone. However, both enzymes have been identified in
breast tissue
CYP1A1 displayed relatively high activity for all three hydroxylations, suggesting that it may play an important role in
extrahepatic tissues where it is expressed
CYP1A1 was more active with regard to 2-hydroxylation and 4-hydroxylation,
it also displayed one of the greatest 16α-hydroxylating activities of the CYP enzymes tested.