CCL2 and esophageal squamous cell carcinoma: Moreover, the CM from imperatorin‐treated ESCC cells were found to reduce the paracrine effect of CAFs on tumor microenvironment by attenuating the in vitro angiogenic activity of HUVECs and invasion of cancer cells induced by CAFs, compared with the CM from untreated ESCC cells, whereas the addition of CCL2 recombinant protein restored the effect (Figure 4J,K; Figure S4C,D, Supporting Information).