DDIT3 and sarcoma: Most importantly, because tumors did not form in Rosa26 LSL-FUS-CHOP/+ or Rosa26 LSL-FUS-CHOP/LSL-FUS-CHOP mice in the presence of intact p53, these data suggest that FUS-CHOP-driven sarcomas in mice are dependent on inactivation of p53 or the p53 pathway.