CXCR4 and neoplasm: CTCE-9908 inhibits human breast tumor cells growth in mouse xenografts impairing the CXCR4–VEGF loop and lowering tumor VEGF levels (Hassan et al., 2011) and affects breast, prostate and esophageal cancer metastasization in murine models (Wong and Korz, 2008; Richert et al., 2009).