The binding assay was also performed in MDCK-SIAT-1 cells which express two-fold higher amounts of alpha-2,6-link sialic acids than parental MDCK cells [26] . The results obtained were similar to that in parental MDCK cells ( Fig. 5C-D) . When cells were treated with bacterial neuraminidase NAvb before fixation with PFA, the binding of sHA proteins was diminished to background level in both MDCK and MDCK-SIAT-1 cells, indicating that the binding of sHA proteins is sialic acid dependent ( Fig. 5C-D) .