For an example, Vag et al. reported that although CXCR4 positivity was seen in vitro in most solid malignancies, including pancreatic carcinoma, laryngeal carcinoma, hepatocellular carcinoma, melanoma, breast cancer, glioblastoma and sarcoma, only low to moderate 68Ga-Pentixafor positivity was noted on PET/CT imaging [27]. The gene discussed is CXCR4; the disease is breast carcinoma.