Primary ER+ (luminal A) (140 ± 84, mean ± SD) and HER2+ (131 ± 66) breast tumors showed higher P-Rex1 expression than primary TNBCs (75 ± 62) (p = 0.027 between luminal A and triple-negative tumors, Figures 1 and 2). This evidence concerns the gene ESR1 and breast neoplasm.