While the P1 promoter-driven isoform is mainly expressed in the liver of adult mice, both P1-HNF4α and P2-HNF4α are expressed in the normal gut39,40,50 (Supplementary Fig. 2F), where only the P1-HNF4α has tumor suppressive activity and aberrant expression of P2-HNF4α contributes to colitis-associated colon cancer28,30. The gene discussed is HNF4A; the disease is colitis.