The insertion site of the gene-trap vector is between exons 21 and 22 of the gene. A truncated transcript is expressed from this allele, as shown by in situ hybridization with a cRNA probe that maps to the 5 end of the transcript, but not full-length transcript. A fusion protein consisting of amino acids 1870 (of 1524) of the endogenous protein fused to the beta-geo reporter is expressed from this allele, in a pattern similar to endogenous expression. (J:255065)