Gel electrophoresis of PCR amplification results using cDNA from three olfactory epithelium tissues, heart, testis, liver, lung, and kidney as template. (a) The 440 base-pair (bp) OBP2B product was only amplified from the olfactory epithelium samples. (b) The 562 bp cathepsin C (CTSC) product was successfully amplified from all three samples. Both primer pairs were designed to amplify multiple exon products and hence are expected to yield a much larger product (1,686 bp) if genomic DNA was used as template. (c) The 378 bp product of the OMP gene was amplified from the olfactory epithelium samples to confirm that these samples contain neutrons.