SP7 and osteosarcoma: As in murine and human osteosarcoma cells, on the other hand, Sp7/Osterix expression has been detected to be reduced versus normal osteoblasts [46], we presume that Sp7/Osterix contents might also be lowered in MG63 and Saos-2 osteosarcoma cells and therefore would exert a minor effect on PDPN promoter activation.