Consistently, MDA-MB-453 (ER−, PR−, HER2+) as well as ZR-75.1 and BT474 (ER+, PR+/−, HER2+) breast cancer cells expressed FGFR4, whereas both FGFR4 and HER2 were low in MCF7 and T47D (ER+, PR+/−, HER2−), and negligible in triple-negative (ER−, PR−, HER2−) cells (Fig. 2a, S1C) [49]. This evidence concerns the gene PGR and breast cancer.