A 248 bp portion of exon 3 and 68 bp of intron 3 were deleted and replaced with a PGK-neo cassette. Western blot of postnatal thymocytes and bone marrow cells indicated absence of protein. Western blot of fetal livers raised against a peptide mapping at the amino acid terminus detected neither full length nor truncated proteins. Northern blot also indicated no full length or truncated transcript. (J:91079)