A. Schematic exon structure of Stim1 gene with conventional exons depicted in grey. Highlighted in red is the alternative exon 11 (named A), and additional mutually exclusive splicing of exon 13 (named L, green) or exon 13 (named B, blue). Alternative usage of 5'UTR regions are indicated with alt1 and alt2. Arrows indicate schematic location of primers, B. Schematic representation of primer annealing sites on the coding mRNA. 