Infection of the murine mastocytoma cell line P815 with different IAV strains (human H1N1, avian H5N1 and H7N2) showed that HIF-1α was activated by H7N2 but not by H1N1 or H5N1 [121], suggesting differing abilities of IAV strains to activate HIF-signalling pathways. This evidence concerns the gene HIF1A and infection.