CXCL16 and Familial prostate cancer: In addition, a correlation between the expression levels of CXCL16 and CXCR6 was found by analyzing an array of forty cases of prostate cancer, and CXCL16 and CXCR6 can be shown to be co-expressed on individual cancer cells by immunofluorescent confocal microscopy (Figure 1E).