Exon 2 was disrupted by the insertion of a construct containing IRES-NLS-lacZ followed by a floxed hygromycin selection cassette. The deleted region included nucleotides 2561 through 2860 (amino acids 149-251) encoding encoding the homeodomain and a conserved NK2-specific domain. Expression of beta-galactosidase was driven by the endogenous promoter. (J:64018)