Zhang et al. discovered that, under conditions of moderate hypoxia, M2 macrophages promote the secretion of IL-1β in HCC via the HIF-1α/IL-1β signaling loop, thereby enhancing tumor metastasis and contributing to the poor prognosis observed in HCC patients (Zhang J. et al., 2018). The gene discussed is IL1B; the disease is hepatocellular carcinoma.