MX1 and cytomegalovirus infection: Studies of HCMV infection in the presence of cycloheximide (CHX) have shown upregulation of IFIT1 (IFI56), IFIT2 (ISG54), IFIT3 (cig49, ISG60), MxA (the protein produced from the Mx1 gene) and ISG15 [31,32,33].