BRF1 and cancer: The TFIIIB subunits, BRF1,20, 21, 22, 23 required for gene‐internal promoters, and BRF2,12, 16, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33 required for gene‐external promoters, distinguish the two forms and have been well‐studied in various human cancers.