Northern blot analysis of agouti expression in BAPa20 and alb-agouti 86 transgenic mice. A Northern blot containing ~2.5 μg of poly (A)+ RNA per lane was hybridized with a radiolabeled agouti cDNA probe. The blot was stripped and rehybridized with a radiolabeled glyceraldehyde-3-phosphate dehydrogenase (Gapd) cDNA probe to control for mRNA loading and quality. The agouti gene is expressed only in the skin of wild-type mice . Therefore, the agouti mRNA detected in these BAPa20 and alb-agouti 86 tissues is transgene-specific.