We report a positive correlation between COUP-TFII and ERα, SRC-1, Pea3, MMP2, and phospho-Src expression, an inverse correlation of COUP-TFII with tumor grade and reduced COUP-TFII in ERα-positive, invasive ductal carcinomas with increased TNM stage within tumor grades II and III and HER2 positivity. Here, ESR1 is linked to invasive ductal breast carcinoma.