EIF2AK2 and viral infectious disease: Phosphorylation of p53 in other amino acid residues in response to IFN or virus infection cannot be excluded since p53 has been also identified as a substrate for the double-stranded RNA (dsRNA) activated protein kinase R (PKR), an IFN-inducible protein kinase which can induce the phosphorylation of human p53 at Ser-392 in vitro [18,19], an event that has been proposed to be related with the stabilization and activation of p53 [20–22].