The gene trap introduced a sequence between exons 3 and 4 of the gene that contains a splice acceptor site (SA), a cDNA encoding the beta-galactosidase reporter linked to neomycin (geo), and a SV40 cleavage/polyadenylation site (pA). While the mutant allele is predicted to generate an ~175-kDa fusion protein, a full length expression product was not detected. Smaller presumptive degredation products were seen on Western blot, albeit at reduced levels. (J:221495)