A genetrap vector containing a beta-gal reporter and a neomycin selection cassette inserted into intron 3 of the gene locus, 2.6 kb downstream of the exon 3. Western analysis on homozygous embryonic fibroblasts indicated protein expression was at 0.8% of the level in wild-type embryonic fibroblasts. Beta gal expression was detected in numerous tissues of homozygotes including cartilage, skeletal muscle, bronchiolar epithelium, and placenta. (J:130238)