Quantitative PCR validation of site-specific microbiota-induced transcriptional responses in the gut epithelium. Tip and crypt epithelial fractions were harvested via LCM from ileum and colon of GF and CR mice. RNA was isolated from each fraction, linear amplified and directly used for quantitative PCR analysis. n = 4 to 5 per group. Data show mean ± standard error of the mean. *P < 0.05, ***P < 0.001, ****P < 0.0001 (two-way ANOVA). ns, not significant; nd, not detectable.