POU2F2 and hepatocellular carcinoma: A neutralization antibody‐mediated blockade of IL‐31 signaling dramatically decreased the levels of POU2F2+ Hep3B or Huh7 cells, whereas recombinant human IL‐31‐mediated activation of IL‐31 signaling had the opposite effect, suggesting that POU2F2+ hepatoma cells have acquired autocrine IL‐31 signaling which conversely stimulates their production (Figure 5D).