Expression analysis of mouse GAD1 splicing isoforms in adult brain. (A) RT-PCR analysis of the expression of GAD1 mRNA splicing isoforms in adult mouse brain by using a forward primer either in Exon1 or Exon2 and a specific reverse primer for each transcript. (B) Analysis of the expression of Isoforms 1 to 6 by using the PCR product of lanes Exon1 and Exon2 in (A) as template for nested PCR with specific primers for each isoform. (C) Gel electrophoresis of Isoforms 3/4 and 5/6, amplified from mouse brain cDNA using specific forward primer and reverse primer, close to the position of the polyadenylation signal. Plasmid containing Isoforms 1/2 was used as a negative control with the primers for Isoforms 3/4 and 5/6 and as a positive control with primers amplifying the 3′-end of Isoforms 1/2. (D) Southern blotting of the gel in (C). The membrane was probed with Probe-GAD1 against 3′-region of Isoforms 1 and 2. Ma, marker λ/HindIII-ϕX174/HaeIII.