LOXL4 and hepatocellular carcinoma: For example, an increase in TAMs induced by lysyl oxidase-like 4 (LOXL4: a copper-dependent monoamine oxidase in the extracellular matrix) in mice has been found mainly due to monocyte infiltration; LOXL4 can inhibit the proliferation of resident macrophages in the liver and nearly deplete the resident macrophages during the formation of HCC [24].