NFKB2 and neoplasm: To determine whether the decreased lung tumorigenesis in NF-κB2–KO mice is caused by NF-κB2 deficiency in immune cells and/or nonimmune cells, and in particular lung epithelial and tumor cells, we generated NF-κB2–KO or WT bone marrow–chimeric (BM-chimeric) mice for the in vivo lung tumorigenesis assays (Figure 2A).