To further explore whether miRNA-21 could inhibit apoptosis in vivo, Tunel assay reflecting severity of myocyte apoptosis and immunohistochemistry staining for cleaved-caspase 3 expression 7 days post infection were performed, compared with control group, percentage of TUNEL positive cells were decreased in miRNA-21 treated group (Fig. 5D), and cleaved-caspase 3 were also down-regulated, which indicates the function of miRNA-21 in the inhibition of apoptosis process in CVB3 infected mice (Fig. 5E). The gene discussed is CASP3; the disease is infection.