Invasion of H9N2 virus affects ISC and Wnt signaling pathways. A–D RT-qPCR analysis of the relative expression of marker genes in ISC (Lgr5, Bmi1) and Wnt signal pathway (wnt3 and Axin2) at 1, 12 and 48 h. E, F RT-qPCR determined relative mRNA expression of Notch pathway genes (Dll1 and Dll4). The results are representative of data from three independent experiments. Each data bar shown represents mean values ± SE of triplicate assays. *P < 0.05; **P < 0.01.