Validation of mRNA microarray data by real-time PCR. Total RNA was extracted from control (CON) and ARDS rat lungs. The expression of mRNAs relative to 18S rRNA was determined by real-time PCR. The results were expressed as a ratio of ARDS to CON. Data are presented as means ± SD from 4 animals, each assay performed in duplicate. *p < 0.05, v.s. CON. Microarray: SAM test; Real time PCR: t-test.