(A) Basal toxicity of pCIG3-CHOP-IRES-GFP relative to prNLS mutants (K103A, S107A, S107E) and the vector control (pCIG3-IRES-GFP) in Vero cells 24h post-transfection. Data are expressed as the fraction of EthD-1 positive (dead) per GFP+ cells; n=9. (B) Exposure of transfected Vero cultures to DMSO vs. Tg (50 nM) reveals conditional toxic properties of CHOP and the various prNLS mutants. Rates of cell death reflect the proportion of EthD-1(+)/GFP(+) cells 24 hours post-transfection; n=4. In both cases, CHOP and C/EBP-β were delivered at a 4:1 ratio. * p ≤ 0.05, *** p ≤ 0.001, **** p ≤ 0.0001.