EGFR and osteosarcoma: Since osteosarcoma is a disease in which 30–80% of cases express EGFR [20,21,22,23,24,25] and the standard chemotherapy involves cytotoxic DNA damaging agents [26], we believed that the Saos-2 model expressing EGFR [27] was the appropriate and relevant in vivo model to demonstrate the effects of targeted combi-molecules carrying a cytotoxic DNA-alkylating moiety.