Also, NEU breast tumors impaired for PKR (PKR−/−) or eIF2α-P (eIF2αS/A) tumors displayed increased proliferation and decreased apoptosis compared with wild type NEU tumors based on immunohistochemistry (IHC) analyses for Ki67 and activated Caspase 3 (Supplementary Fig. 2). Here, EIF2AK2 is linked to breast neoplasm.