{"knowledge_schema": {"broad_category": "Biology \u2192 Immunology \u2192 Antibody Interactions", "refinement": "This problem focuses on the experimental design to study the binding of antibodies to specific glycoproteins, particularly the role of tags and controls in verifying results.", "specific_scope": "The context involves the use of a flag tag on MUC1 expressed in a specific cell line to assess the binding of an antibody in the presence of a glycan inhibitor (GalNAc).", "goal": "To ensure accurate interpretation of the results by verifying that the surface expression of MUC1 is unaffected by the presence of GalNAc."}, "summary": "In this experimental setup, it is crucial to include the anti-flag antibody to verify that the presence of GalNAc does not alter the surface expression of MUC1. This verification is essential for interpreting the binding results accurately. The anti-flag antibody should be added with the primary antibodies to ensure that any observed effects on antibody binding can be attributed to the glycan's role rather than changes in MUC1 expression."}