By contrast, in AFP464-resistant ERα-negative basal B subtype breast cancer cell lines (Hs578T and MDA-MB-231), AhR was either undetectable at the protein level (e.g., Hs578T) or predominantly localized in the nucleus (e.g., MDA-MB-231) (Figure 1A and 1B). Here, ESR1 is linked to breast cancer.