Truncated EGFP-RIG1 fusion proteins induced cell death and apoptosis. (A) HtTA cells were transfected with 0.3 μg of indicated recombinant RIG1 expression vectors for 24 or 48 h. Cell death was detected by measuring LDH release and cell viability was measured using the MTT method. Representative results of three independent experiments are shown and are expressed as means and standard errors of the means after normalization to the control group. (B) Cells were transfected with indicated expression vectors for 48 h. Cells were stained with Hoechst 33258 dye, and chromatin condensation was evaluated with a fluorescent microscope. Arrows indicate cells expressing the EGFP or RIG1 fusion protein that were positive for chromatin condensation. Scale bar: 1 μm. (C) Cells were transfected with indicated expression vectors for 24 h. The activation of caspase-3 was assayed using the colorimetric substrate Ac-DEVD-pNA. wt: wild type; Student t test: *, P < 0.05; **, P < 0.01; ***, P < 0.001.
Tsai et al. BMC Cell Biology 2009 10:15 doi:10.1186/1471-2121-10-15