A loxP site was inserted upstream of eoxn 2. A floxed neo cassette was inserted downstream of exon 3. Cre-mediated recombination removed exon 2, exon 3, and the neo cassette. Aberrant splicing between exons 1 and 4 is predicted to produce a premature stop codon in exon 4 due to a frameshift. The absence of protein expression was confirmed by western blot analysis of cerebellar extracts. (J:89899)