Together, our results confirmed that the CD133+ population in prostate cancer cells and CD44+/high/CD24−/low population in breast cancer MCF7 cells possessed typical stemness-associated characteristics, consistent with previous reports.9, 32, 33, 34, 35, 36 Thus, these cells, hereafter referred to as CSCs, were further used to understand the signaling mechanisms activated by neuropeptides. This evidence concerns the gene CD44 and breast cancer.