To validate the roles of IL‐31 on inducing POU2F2 expression and giving rise to HCC, mice with a hepatocyte‐specific knockout of IL‐31 (termed IL‐31ΔHep) were i.p. injected with TAM starting 4 months post‐DEN to specifically delete hepatic IL‐31. The gene discussed is IL31; the disease is hepatocellular carcinoma.