HIF1A and neoplasm: To support the idea that tumor cell‐derived lactate is sufficient to alter the HIF‐1α/STAT3 signaling pathway, conditioned medium (CM) from MC38 cells was applied to macrophages and upregulated HIF‐1α/phosphorylated STAT3 was observed in WT macrophages, indicating that NAMPT promotes this pathway (Figure 2D).