To determine whether C/EBPβ is essential for the survival of oncogenic Ha-Ras skin tumors, we developed a mouse model, K14-CreERtam;C/EBPβflox/flox (IKOβ), in which C/EBPβ could be conditionally and temporally deleted in the epidermis and in pre-existing oncogenic Ha-Ras skin tumors (Fig. 1b). This evidence concerns the gene CEBPB and skin neoplasm.