RUNX2 and osteosarcoma: We further investigated if other potential mediators of biglycan action involved in key developmental processes such as BMP, Wnt/β-catenin, RUNX2, HIPPO/YAP or IGF-IR are “hijacked” by osteosarcoma (45) Previously, IGF-I was shown to be an important enhancer of osteosarcoma cell survival facilitating growth and attenuating apoptosis (46).