USF1 and osteosarcoma: While loss of USF activity is implicated in multiple solid tissue cancers including breast [4], ovarian [5], prostate [6], oral epithelial [7], gastric, and skin cancers [8–10], multiple studies have paradoxically shown that USF1 in particular can promote cancers such as cutaneous squamous cell carcinoma, melanoma, cervical cancer, and osteosarcoma [11–15].