TLR4 and neoplasm: CCL17 expression in M2 macrophages can activate Wnt/β-catenin signaling and promote EMT of tumor cells, while tumor cells in turn activate TAMs through the TLR4/TRIF/NF-κB signaling pathway and increase IL-1β production mediated by HIF1α to trigger EMT (Zhu et al., 2016).