CXCR4 and thyroid gland carcinoma: For all receptors, but especially SST2, SST4, SST5, and CXCR4, expression levels varied considerably among the individual patients, which is reflected by the large number of outliers and the length of the boxes and whiskers depicted in Fig. 3A. However, SST and CXCR4 expression levels were generally very low in the thyroid cancer samples investigated.