EIF2AK2 and influenza: Based on data from the Influenza Research Database [52], we analyzed the prevalence of Influenza_A_NS1_SF33 and Influenza_A_NS1_SF30 SF-VTs corresponding to crk/crkL and PKR-binding sites, respectively, for each of the NS1 classes proposed here using the unique sequence database pdb4535 (Table 6).