Interestingly, basal PKR phosphorylation at threonine 451, a critical site of PKR autophosphorylation, was dramatically higher in breast cancer cell lines MCF7, T-47D and MDA-MB-231 compared to the “nontransformed” mammary epithelial cell line MCF10A (Figure 3A). This evidence concerns the gene EIF2AK2 and breast cancer.