This immunophenotype is highly consistent with the phenotype of GFP+ cells isolated from primary histiocytic sarcomas induced by intramuscular injection of p16p19−/−; Kras(G12V) BM cells (see Fig. 2D), as well as the phenotype of GFP+ leukemia cells derived by retro-orbital injection of BM cells modified by the same oncogenetic lesions (see Fig. 1E). The gene discussed is KRAS; the disease is histiocytic sarcoma.