ESR1 and breast cancer: Subsequently, we compared cMLC-1 levels among the 4 major molecular subtypes of BC patients (n=79): Luminal A (estrogen-receptor (ER)+ or progesterone-receptor (PR)+, HER2-, n=35), Luminal B (ER+ or PR+, HER2+, n=34), HER2-enriched (ER-, PR-, HER2+, n=6) and triple negative breast cancer (TNBC) (ER-, PR- and HER2-, n=4) (20, 21).