ENU-induced G to A transition at base pair 135,613,943 (v38) on chromosome 3, or base pair 78,040 in the GenBank genomic region NC_000069 encoding Nfkb1. The mutation corresponds to residue 1,292 in the mRNA sequence NM_008689 within exon 10 of 25 total exons. The mutation results in a glutamic acid to lysine substitution at position 264 (E264K) in the NFKB1 protein.