The expression of PDK1 was significantly upregulated in 143B OSCs rather than in 143B non-OSCs (Fig. 3C), consistent with findings in the OSC population of primary osteosarcoma specimens (Fig. 2B), along with significant upregulation of stem cell markers, such as SOX2, KLF4, and ABCG1 (Fig. 3D) [48–52]. This evidence concerns the gene SOX2 and osteosarcoma.