The unsupervised classification of CXCL12 expression values defined 2 groups of samples with the optimal model, which corresponded to a high CXCL12-expressing group (n = 221) that contained 100% of the non-tumor samples and a second group that expressed less CXCL12 (n = 481) (Figure 1B). Here, CXCL12 is linked to neoplasm.