The transgene consists of a Camk2a promoter fused to a Fyn isoform B cDNA carrying a TAT to TTT nucleotide substitution at codon 531. Camk2a drives expression in forebrain neurons late in development. This mutation renders Fyn constitutively activated. Transgene expression in the brain was confirmed by Northern blot, RNase protection assay, RT-PCR, and in situ hybridization.