CD133 (AC133), a member of prominin family, is a glycoprotein with 3 isoforms that has been wildly used for isolating CSCs. Several studies have linked CD133-positive cells with a stem-cell phenotype. These include CD133-positive subpopulations exhibiting stem-like properties in SAOS2, MG63 and U2OS osteosarcoma cell lines [19], [20] and [21]; elevated mRNA expression levels in stemness genes Oct4, Nanog and CXCR4 [22] and [23]; higher migration and invasive capabilities, particularly in lung metastasis [24]; and increased drug resistance [22] and [23]. In addition, cell populations with elevated levels of CD133 and CD199, along with low levels of CD44, exhibited higher levels of stem cell markers [25]; and CD49f-negative/CD133-positive cells possessed strong tumorigenicity and self-renewal capacities and were able to differentiate to CD49f-positive cells with more limited tumorigenicity [26].