CXCR4 and cancer: Previous studies have shown an increased expression of CXCL12 and CXCR4 which allowed migration of cancer cells to metastatic organs such as lung, liver and bone and brain via a CXCL12–CXCR4 chemotactic gradient which leads towards metastasis (Cavallaro, 2013; Hinton, Avraham & Avraham, 2010; Liberman et al., 2012; Salomonnson et al., 2013; Sun et al., 2014).