MKI67 and breast neoplasm: However in the recent times the global gene expression studies have identified breast tumors further into distinct molecular classes based on the expression level of endocrine receptors, proliferative genes, oncogenes and other genes; luminal A (ER+/PR+ and Ki67 high), luminal B (ER+/PR+, Ki67 low or, ER+/PR+/HE R2+), HER2+, basal (ER-/PR-/basal myoepithelial markers high/ EGFR+), and normal breast-like (ER-/PR-/basal myoepithelial markers-/EGFR-) (Yersal and Barutca, 2014).