HGF and osteosarcoma: Many cell lines have been used for evaluating the cytotoxicity of endodontic materials including mouse gingival fibroblasts, human osteosarcoma cell line [20], V79 fibroblasts, murine granulocyte-macrophage progenitor cells [21], HGF [22, 23], Hela cells [24, 25] and fibroblasts of periodontal ligament [26].