NR2F2 and breast cancer: COUP-TFII is not expressed in basal-like, triple negative, dedifferentiated MDA-MB-231 and is lower in tamoxifen (TAM)/endocrine-resistant LCC9 and LY2 breast cancer cells than in parental endocrine-sensitive MCF-7 cells, whereas COUP-TFI expression is similar [13], suggesting a role in maintenance of differentiation and endocrine sensitivity.