INS and osteosarcoma: The fact that [AspB10]insulin has induced a higher incidence of breast cancer in a 1-year toxicity study in Sprague-Dawley rats [20] and a higher proliferation rate of the osteosarcoma cell line Saos-2 [12] has led to the contention that insulins with a profile in vitro similar to [AspB10]insulin might also have a potential tumor-promoting activity.