ESR1 and breast cancer: Positive correlations were observed between pSTAT1 and pRPA expression in all the breast cancer subgroups (r = 0.269, P < 0.001 in ER+/HER2- cases, r = 0.226, P = 0.021 in HER2+ cases and r = 0.213, P = 0.047 in TNBC).