IR and IRS-1 protein levels while HCV E2 protein expressed in Huh7. Huh7 cells were transfected with FLAG-CMV2 or FLAG-E2 for 24 hours and then subjected to western blotting for IR and IRS-1 with β-actin acting as internal control (A). Relative photographic density was quantified and the results were shown as histograms mean relative IR (B) and IRS-1 (C) levels after being normalized by β-actin. While the protein level of IR was unchanged, that of IRS-1 protein expression was decreased by HCV E2 expression. The error bars represented standard deviation from triplicate experiments. * indicates p<0.05.