CXCR4 and neoplasm: To the best of our knowledge there are only two studies available on CXCR4 expression in GEP-NEN so far15,16 comprising 64 and 61 cases, respectively; for an overview of the studies of the last 15 years on SST expression in GEP-NEN, including the number of cases evaluated, the SSTs studied, the type of antibodies used and if correlations were performed with tumor functionality, location, grading/staging, Ki-67 index, CgA expression, SST-based imaging or patient outcomes, see Supplementary Table 4.