The function of MAFB (MAF bZIP transcription factor B, ENSG00000204103) is as follows. Acts as a transcriptional activator or repressor (PubMed:27181683). Plays a pivotal role in regulating lineage-specific hematopoiesis by repressing ETS1-mediated transcription of erythroid- specific genes in myeloid cells. Required for monocytic, macrophage, osteoclast, podocyte and islet beta cell differentiation. Involved in renal tubule survival and F4/80 maturation. Activates the insulin and glucagon promoters. Together with PAX6, transactivates weakly the glucagon gene promoter through the G1 element. SUMO modification controls its transcriptional activity and ability to specify macrophage fate. Binds element G1 on the glucagon promoter (By similarity). Involved either as an oncogene or as a tumor suppressor, depending on the cell context. Required for the transcriptional activation of HOXB3 in the rhombomere r5 in the hindbrain (By similarity). {ECO:0000250|UniProtKB:P54841, ECO:0000269|PubMed:19143053, ECO:0000269|PubMed:27181683}.