During the early stage of tumour metastasis in breast cancer [73–75], colorectal cancer [76] and hepatocellular carcinoma [77], hypoxia acting as an important primary tumour microenvironmental factor regulates PMN formation through inducing the several members of LOX family, including LOX, LOX-like (LOXL) 2 and LOXL4. This evidence concerns the gene LOXL4 and neoplasm.