Figure 5 illustrates miRNA and epigenetic variation causing drug-resistant BC. miR-33a, miR-298 and miR-1246 cause radiation resistance, doxorubicin and multi-drug resistance, respectively. Also, miR-27b downregulation leads to nischarin resistance. Epigenetic variations like CTCF hypermethylation and histone3 acetylation have been observed to show tamoxifen and doxorubicin resistance, respectively [67,102,104,106,108,110,111]. Here, CTCF is linked to breast cancer.