Five intrinsic subtypes of breast cancer were initially identified: Luminal-A, Luminal-B, HER2+, triple negative/basal like (TNBC) and normal like, which is based on the gene expression of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) (2). The gene discussed is PGR; the disease is breast cancer.