RUNX2 and neoplasm: Regardless of the hypothesis, the expression of markers such as RUNX2 (Runt-related transcription factor 2), ALP (alkaline phosphatase), OCN (osteocalcin), and BSP (bone sialoprotein) by OS cells suggests that this tumour originates from the deregulation of the differentiation program of cancerous or non-cancerous MSCs [133,134].