Effect of TLR3 knock-down on poly(I:C)-induced apoptosis in SK-N-AS cells. After transfection with siRNA (60 nM) for 24 h, the cells were incubated with poly(I:C) 50 μg/ml or vehicle for another 24 h and were then harvested for assay. C, control; LI, lipofectamine; SC. Scramble control siRNA; siTLR3, TLR3 siRNA. (A) Effect of TLR3 siRNA knockdown on poly(I:C)-induced caspase-3 activation. Arrows indicated the molecular weight of active caspase-3 at 17 and 19 kDa, respectively. Quantification results of caspase-3 activation in different treatment groups were expressed as mean ± SD from triplicate experiments (bottom panel). *: P < 0.05, **: P < 0.01. (B) Flow cytometry analysis of poly(I:C)-induced apoptosis in SK-N-AS cells after TLR3 siRNA knockdown. Data were mean ± SD from triplicate experiments. **: P < 0.01. (C) Cell proliferation assay of poly(I:C)-induced growth inhibition in SK-N-AS cells after siRNA knock-down of TLR3. Data were mean ± SD from triplicate experiments. *: P < 0.05.