BCR and follicular lymphoma: As a model for the ligand–receptor interaction, we used transgenic Raji-FL cells that express membrane-tethered BCR (B-cell receptor) in a single-chain format, derived from a patient with follicular lymphoma cells, and its peptide ligand P#1 (CILDLPKFC) [30,32] cloned into the phage vector (P#1-HA-p3-fADL-1e or P#1-flag-p3-fADL-1e).