DUSP4 and viral infectious disease: Dual specificity protein phosphatase 4 (DUSP4) gene was downregulated in SARS-CoV infection with the association with the skew of Th1 toward Th2 immune response leading to susceptibility to viral infections and inflammation, however, may control the occurrence of cytokine storm by IL-6, IL-12 and tumor necrosis factor α (TNFα) as well as increasing the amount of prostaglandin PGE2 [59].