Detection of IRF5 in A20 Mouse Cell Line by Flow Cytometry. A20 mouse B cell lymphoma cell line was stained with Rat Anti-Mouse IRF5 PE-conjugated Monoclonal Antibody (Catalog # IC8447P, filled histogram) or isotype control antibody (Catalog # IC013P , open histogram). To facilitate intracellular staining, cells were fixed with Flow Cytometry Fixation Buffer (Catalog # FC004 ) and permeabilized with Flow Cytometry Permeabilization/Wash Buffer I (Catalog # FC005 ). View our protocol for Staining Intracellular Molecules .