CSCs seem to play an important role in the initiation and development of various malignancies [29-31]. The detection of CSCs in solid cancers was firstly confirmed in 2003, by Al-Hajj et al., who showed that only a fraction of CD44+/CD24+ or negative breast cancer cells could create a tumor with the same characteristics of the initial tumor [32]. This evidence concerns the gene CD44 and breast carcinoma.