ENU-induced A to C transversion at base pair 22,675,036 (v38) on chromosome 8, or base pair 31,556 in the GenBank genomic region NC_000074. The mutation corresponds to residue 859 in the mRNA sequence NM_001159774 (variant 1) within exon 9 of 22 total exons. The mutation results in an isoleucine to leucine substitution at position 243 (I243L) in both isoforms of the inhibitor of kappa-B kinase- (IKK-; alternatively, IKK-2) protein.