The upregulated differentially expressed breast cancer stem cell markers included CD56/NCAM1, POU5F1, PROCR/CD201, ITGA6, and the downregulated were ESR1, PGR, HER2/ERBB2, ABCG2, CD44, CD24, EPCAM, and CDH1 (Figure 3K). Here, ABCG2 is linked to breast cancer.