EIF2A and breast cancer: To further investigate whether induction of eIF2α phosphorylation may promote breast cancer cell sensitivity to DOX, we treated MCF7, T-47D and MDA-MB-231 cells either expressing control or PKR siRNA with salubrinal, a specific inhibitor of eIF2α phosphatase that has been reported to cause an increase in the level of phosphorylated eIF2α [40].