CD44 and breast cancer: CSCs are characterised by specific surface markers such as CD133+/CXCR4+, CD24+/CD44+, CD24+/CD44+/ESA+, c-Met+/CD44+, and ALDH1+/CD133+ in pancreatic cancer [27, 28]; CD24−/low/CD44+ in breast cancer; CD44+ in colon/ gastric/ head and neck/ovarian cancer; CD34+/CD38− in leukaemia cells; CD13/CD45/CD90 in liver cancer; CD117/CD90/EpCAM in lung cancer; CD20/CD166/Nestin in melanoma cancer; and CD133+/ABCG2+ in Glioblastoma Multiforme [29, 30].