When inoculated into the colonic mucosa of wild-type and Rag1–/– immunodeficient mice (lacking T and B cells), tumors developed in immunodeficient mice with p53 loss, KrasG12D mutation, or both, whereas Apc loss allowed tumor formation in both WT and immunodeficient mice (Fig. 1c, d; Supplementary information, Fig. S1b, c). The gene discussed is RAG1; the disease is neoplasm.