The targeted locus was disrupted by the insertion of a neomycin selection cassette into exon 5. Transcripts 1.5 kb longer than wild-type, putatively resulting from the incorporation of the neo transgene, were detected in homozygous mutant embryos via Northern blot analysis. Western blot analysis of lysates obtained from homozygous mutant embryos showed a lack of normal protein. The absence of a truncated peptide encoded by sequence upstream of the insertion could not be confirmed due to the lack of an appropriate antibody. (J:48123)