EIF2AK2 and neoplasm: To confirm that through the induction of apoptosis PKR activation is involved in the synergistic effect exerted by 5-FU/IFNα combined treatment, we first set up the conditions by which either, 5-FU or IFNα (i.e, 5 μM of 5-FU and 500 IU/ml of IFNα) did not induce or induce low levels of apoptosis under our experimental conditions in the different tumor cell lines (Figure 4).