Exogenous HGF significantly chemoattracted the migration of M2 macrophages but not M1 macrophages (Fig. 6a), suggesting that HGF secreted by M2-like TAMs may recruit more macrophages in tumour tissues, regulate the distribution of M2 macrophages and increase tumour resistance to sorafenib in a feed-forward manner. The gene discussed is HGF; the disease is neoplasm.