IFIT1 and viral infectious disease: More importantly, blockage of the cleavage (D126A) significantly increased the IFN-β promoter activity (Fig. 6K and O), mRNA levels of IFN-β and ISGs (IFIT-1 and MX1) (Fig. 6L to N and P to R), and IFN-β production in the supernatants (Fig. 6S), especially at the late stage of virus infection and poly(I·C) treatment.