SDS-PAGE: 4-12% Bis-Tris gel Lane 1. 5 µg IgM (reduced/heated) Lane 2. 10 µg IgM (reduced/heated) Lane 3. 20 µg IgM (reduced/heated) Lane 4. Molecular weight markers Lane 5. 5 µg IgM (non-reduced/no heat) Lane 6. 10 µg IgM (non-reduced/no heat) Lane 7. 20 µg IgM (non-reduced/no heat)