The gene-trap vector (beta-geo) is inserted downstream of exon 38. The mutation results in the removal of the C-terminus of the gene, including a proline-rich domain and the Cytoskeleton-Associated Protein Glycine-rich (CAP-Gly) domain (amino acids 1521-1843). The expression of truncated protein is not identifiable by Western blotting, but can be identified by LacZ staining of embryos and mouse embryonic fibroblasts. (J:282570)