Adhikari et al. found that sphere cells generated from the mouse osteosarcoma cell lines K7M2, 318-1, and P932 possessed characteristics of CSCs such as having increased tumorigenicity when injected subcutaneously into mice, increased expression of the drug transporter ABCG2, and an ability to differentiate into multiple lineages (osteogenic and adipogenic). Here, ABCG2 is linked to osteosarcoma.