The four intrinsic molecular subtypes of BC are luminal A (ER+, PR+, and HER−, the most common), luminal B (ER+, PR+, and HER+), HER2-enriched (ER−, PR−, and HER+), and triple-negative (ER−, PR−, and HER−) (48). The gene discussed is ERBB2; the disease is breast cancer.