CXCR4 and cancer: However, our studies show that human cancer cells are able to invade zebrafish blood vessels and form secondary tumours, which can be inhibited by specific autophagy inhibition (Verykiouet al., 2018); while previous studies have shown that VEGF and CXCR4 signalling are conserved between human cancers and zebrafish (Heet al., 2012;Tulottaet al., 2016).