A gene trap vetor containing a beta-geo cassette was inserted into intron 2. Insertion was confirmed by PCR genotyping and expression of the lacZ gene was confirmed by beta-galactosidase staining. Two transcripts were detected by RT-PCR: one the expected fusion of exon 1 and 2 to the gene trap vector sequence and the other an alternative transcript lacking exon 2. (J:126878)