A promoter trap strategy was used to replace exons 3 and 4 with an SA-IRES-betageo-pA cassette. The resulting protein encoded from the locus would contain only the five N-terminal amino acids fused to lacZ-neo, thereby inactivating both the full-length and the proposed short form of amyotrophic lateral sclerosis 2 (juvenile) homolog. Absence of protein was confirmed by Western blot analysis of cortex, cerebellum and testis.