Characterization of the NS1-Hsp90 interaction in A549 cells by Coimmunoprecipitation. A549 cells were co-transfected with the plasmids encoding Myc-tagged NS1 (A. H5N1; B. H3N2) and Flag -tagged Hsp90. Cell lysates were immunoprecipitated with anti-Myc antibody to capture NS1 and coimmunoprecipitated Hsp90 was detected by immunoblotting with anti-Hsp90 antibody. Lysates were prepared as in described above, but immunoprecipitated with anti Flag antibody to capture Hsp90, and the associated NS1 of H5N1 was detected by immunoblotting with anti-Myc antibody. (5NS1 represent NS1 of influenza H5N1; 3NS1 represent NS1 of influenza H3N2).