look at this

https://www.nature.com/articles/bjc2014166

MCF7

Aromatase inhibitors target production of E1 and E2 in postmenopausal women, which can occur in numerous sites, such as adipose tissue, skin...etc., and not just locally in breast cancer cells. For this reason, the relevance of models based on the expression of aromatase solely in breast cancer cells is somewhat limited. Still, breast cancer cell line expressing aromatase had been reported, such as MCF-7 transfected to express aromatase (MCF-7Ca, not just MCF-7 cells). Frequently used breast cancer cell lines do not normally show appreciable expression of aromatase. In fact, much higher expression was found in some cell lines derived from other cancers, such as gliomas and melanomas.

MCF-7