(45) by using gene expression profiling (GEP) on 456 cDNA clones of the breast, classified human breast cancers into five intrinsic subtypes, i.e., luminal A (ER+, PR+, HER2-, KI67-), luminal B (ER+, PR+, HER2+/-, KI67+), HER2 over-expression (ER-, PR-, HER2+), basal-like (ER-, PR-, HER2-, CK5/6+) and normal-like tumors (ER+, PR+, HER2-, KI67-). The gene discussed is ESR1; the disease is breast cancer.