CEBPB and Ewing sarcoma: Furthermore, mice with oncogenic Ras tumors have been shown to be dependent on CEBPB for their survival with deletion of CEBPB in pre-existing oncogenic Ha-Ras mouse skin tumors in vivo, resulting in rapid regression [49], while, in an in vitro model of Ewing sarcoma, overexpression of CEBPB led to a significant increase in colony formation, which was depleted when CEBPB was deleted [50].