Analysis of BRP-39, Ym1 and Ym2 reference gene mRNAs in lung and stomach tissues. The expression levels of the eight genes determined using the cDNAs prepared from lung (A) or stomach (B) tissues from 3-month-old mice (n = 5) were quantified by real-time PCR. All of the values are expressed as number of molecules per 10 ng of total RNA in y axis. The upper panel indicates the actual value, and the lower panel shows each value on logarithmic scale. The expression level of the mouse Chit1 gene was set to 1.0; the values above the bars indicate the relative expression levels compared to the expression level of the mouse Chit1 gene. Data are presented as mean ± SD of five samples. *p < 0.05; **p < 0.01.