Western blotting analysis of Vo and Vi material from the gel filtration column using rabbit anti-MUC5B and goat anti-MUC7 polyclonal antibodies. a) Lanes 1, MUC7 (negative control), 2 and 3, Vo material from two donors and 4, respiratory MUC5B (positive control) and in b) Lanes 1, crude saliva (positive control), 2, gastric mucin (negative control) and 3, purified Vi material were separated by 10% SDS-PAGE and transferred to nitrocellulose membrane. Following overnight blocking, the membranes were incubated for 2 h with rabbit anti-MUC5B (a) and goat anti-MUC7 (b) polyclonal antibodies. Membranes were then incubated for 1 h with goat anti-rabbit (a) and rabbit anti-goat (b) HRPO linked secondary antibodies and bands that interacted with the antibodies were detected by exposing the membrane to ECL detection. The arrows indicate the two glycoforms of MUC7.