Figure 7. Phosphorylation of eIF2α increases breast cancer cell line sensitivity to doxorubicin. A.

. Western blotting using antibody specific for phosphoserine-51 eIF2α (P-eIF2α), eIF2α or actin demonstrates increased eIF2α phosphorylation in breast cancer cell lines following 48 hours treatment with 20 µM salubrinal. B.–D. Breast cancer cell lines either expressing PKR siRNA (siPKR) or control siRNA (siControl) were treated with either 2.5 µM DOX (+ DOX) or co-treated with 2.5 µM DOX and increasing concentrations of salubrinal for 48 hours. Viability was measured by Trypan blue dye exclusion assay. Experiments were repeated in triplicate and mean ± SD graphed. Statistical significance was determined by t-test. * Indicates p<0.05, ** indicates p<0.01 compared to DOX treatment alone.