Finally, in order to demonstrate that miR-US5-2 regulation of UL138 protein expression operates through modulation of EGR1 levels during infection, we transfected human fibroblasts with negative-control miRNA, miR-US5-2 mimic, or siRNAs targeting GAB1 or EGR1 followed by infection with WT virus or a ΔEGR-1 mutant virus where an EGR1 binding site upstream of the UL138 transcriptional start site, previously shown to regulate UL138 expression in response to EGF, was mutated (14). This evidence concerns the gene GAB1 and infection.