Since lacking transactivation domain, small Mafs participate in tumor progression through forming heterodimers with the CNC family proteins p45 (large nuclear factor erythroid 2 (NF-E2) subunit), Nrf1 (NF-E2-related factor 1), Nrf2, and Nrf3, as well as Bach1 and Bach2 [149]. The gene discussed is NFE2; the disease is neoplasm.