NR4A1 and breast cancer: In comparison to the triple-negative breast neoplasm cells (HCC1806, HCC1937, MDA-MB-231, and BT549), hormone receptor-positive breast cancer cells (MCF-7), and human epidermal growth factor receptor-positive cells (SK-BR-3), THEM6 mRNA expression was significantly lower in the non-tumorigenic breast epithelial cells (MCF-10A) (Fig. 8A).