PROM1 and osteosarcoma: Because of their apparent change in morphology and ability to form spheres in the HFB environment and because others have demonstrated the presence of CD133(+) cells within primary bone sarcomas, as well as the osteosarcoma cell lines MG-63, OS-521, 0S-01-187, OS-99-01, and SAOS-2 and the chondrosarcoma cell line CS-828 [32], [33], we hypothesized that the HFB selected cells were CD133(+).