Interestingly, in accordance with the assumption that SSEA-4+ osteosarcoma cells differentiate to produce SSEA-4− cells, analyses of pathways revealed significant upregulation of several mesenchymal differentiation signature genes, such as RUNX2, BMPR2, COL3A1, IBSP and ADIPOQ, in SSEA-4− cells (Fig. 3a and Supplementary Fig. 3a)33, 34. This evidence concerns the gene COL3A1 and osteosarcoma.