ESR1 and cancer: These are ordinary-like (with expression profile as non-cancer breast tissue); luminal A and B (mostly estrogen receptor ER+ cancers, with an expression of epithelial markers; luminal B exhibit high Ki67 index and more terrible anticipation contrasted with luminal A); HER2+ (high expression of oncogene- ERBB2); basal-like (expressing basal cytokeratin and different markers normal for the myoepithelium of the typical mammary organ); and claudin-low [enhanced in epithelial-to-mesenchymal transition (EMT) highlights, immune system responses, and stem-cell related natural cycles].