To examine the mRNA levels of STARD3 among BC subtypes, namely, luminal A, luminal B, HER2+ and TNBC, we used several BC cell lines: ER+ (MCF7, T47D, and BT-474), HER2+ (BT-474, SKBR3, and HCC1419), triple-negative (MDA-MB-231 and MDA-MB-436), and a normal cell line (MCF 10A) (Figure 2A). The gene discussed is ESR1; the disease is breast cancer.