Inflammatory cytokines in tissues of H9N2-infected chickens. Total RNA was collected from tissues of infected or uninfected chickens (n = 5 per group) with A/Chicken/Korea/S21/2004 (H9N2), and cytokines were quantified using primers specific for chicken cytokines and SYBR Green-based real-time PCR. Data represent the mean ± standard error of five chickens. Panels A, B, and C depict results from trachea, lung, and intestinal tissue. Statistical analysis was performed by the comparison of data of uninfected chickens. [*P < 0.05], [**P < 0.001].