HGF from M2 macrophages and tumour cells activates HGF/c-Met, MAPK/ERK1/2, and PI3K/AKT pathways in tumour cells, recruits more macrophages from surrounding blood circulation, regulates the distribution of M2 macrophages in tumour tissues, and increases tumour resistance to sorafenib in a feed-forward manner (Fig. S4). The gene discussed is MET; the disease is neoplasm.