Chemicals. DON, anisomycin, PKR inhibitor C-16, and Hck inhibitor PP1 were purchased from Sigma-Aldrich (St Louis, MO). Ricin was obtained from Vector Labs Inc. (Burlingame, CA). SG was purified as described previously (Islam et al., 2009) . The p38 inhibitor SB 203580, JNK inhibitor SP600125, ERK inhibitor PD 98059, RNase L Activator, p53 inhibitor pifithrin-a, and pifithrin-l were purchased from EMD Chemicals Inc. (Gibbstown, NJ). Pan caspase inhibitor Z-VAD-FMK was supplied by BD Biosciences (San Diego, CA). [c-32 P]ATP was purchased from PerkinElmer. All other chemicals and media components were obtained from Sigma-Aldrich, except where noted.