Co-culturing MCF-7 breast cancer cells with CAFs induces higher mammosphere formation and stem cell-related gene expression including Wnt1, Notch1, β-catenin, chemokine receptor (Cxcr) type 4, Sox-2, and aldehyde dehydrogenase 3 family member A1 (Aldh3a1), compared to those with the MCF-7 breast cancer cells co-cultured with normal mammary fibroblasts [137,138]. This evidence concerns the gene NOTCH1 and breast cancer.