The potency of Furaprofen against the replicon is also confirmed by both Western blotting and TaqMan RT-PCR to be about 37 nM and 54.67±4.11 nM, respectively. The antiviral activity of Furaprofen has been determined by a reporter replicon assay with multiple repeats to be 29.88±8.05 nM, an ~3-fold improvement over the activity of the parent compound, R706. To assess the general effect of Furaprofen on cell proliferation, a panel of primary cells and transformed human cell lines are treated with increasing doses of Furaprofen for 48 h, and the effect on cell proliferation is measured by an MTS-based cell viability assay. The concentration that caused a 50% reduction in cell numbers in the absence of virus infection (CC50) of Furaprofen is found to range from 2 μM to ≥10 μM, depending on the cell type and proliferation status[1].