FOXO1 and alveolar rhabdomyosarcoma: Indeed, decreased p16INK4a levels were observed in ARMS cell lines that are PAX3-FOXO1–positive but not in ERMS cell lines that are PAX3-FOXO1–negative, further indicating the functionally significant association between PAX3-FOXO1 expression and the loss of p16INK4a function in promoting ARMS tumor formation [4].