RUNX2 and osteosarcoma: Furthermore, overexpression of Runx2 reversed the suppression of cell migration and invasion induced by knocking down CBX4 (Fig. 2k), while depletion of endogenous Runx2 abolished the enhancement of both migration and invasion induced by CBX4 overexpression (Fig. 2l), indicating that the effects of CBX4 on osteosarcoma cell migration and invasion depended on Runx2.