The expression of MCM2 correlated positively with the grade of malignancy and negatively with estrogen receptor (ER) and progesterone receptor (PR) expression in invasive ductal breast carcinoma (IDC), which helps distinguish luminal A from luminal B, Erb-B2 receptor tyrosine kinase 2 (HER2)-positive, and TNBC (Issac et al. 2019; Wojnar et al. 2011). Here, ESR1 is linked to invasive ductal breast carcinoma.