IRF4 and fibrosarcoma: Tfh cells also express a series of transcription factors, such as Signal transducer and activator of transcription 3/4 (STAT3/4), Transcription factor B-cell lymphoma 6 (Bcl-6), Interferon regulatory factor 4 (IRF4), c-musculoaponeurotic fibrosarcoma (cMaf), and show a similar relationship with Th effector subsets (138).