HAS2 and neoplasm: Furthermore, Nobutaka Kobayashi et al. have developed a HA synthase 2 gene conditional knockout mice to prove that hyaluronic acid secreted by tumor cells can bind to TLR4 on the surface of macrophages, induce TAMs to migrate to tumor-related areas [172], and inhibit the expression of C/EBPβ through miR935 to promote the differentiation of macrophages into M2 Macrophages [173], thereby promoting malignant tumor cells to avoid immune surveillance and “cool down” the immunoreaction.