Strategy for comparing the gene expression levels of five genes.

<p>The expression levels of the Chit1 and AMCase genes were compared. To evaluate the chitinase levels, we used two housekeeping genes, GAPDH and β-actin, which are constitutively expressed at high levels in most tissues and cells. In addition, we chose pepsinogen C, which is a major component of the gastric mucosa, as a reference gene for the stomach tissues. Using these three reference genes, we evaluated the gene expression levels of Chit1 and AMCase in mouse tissues.