CXCL12 and colon adenocarcinoma: TCGA data confirmed that CXCL12 and SPHK1 expression correlated in COAD tumor samples, but not in normal colon tissue (Fig. 6I), suggesting that ramping up CXCL12 and S1P production by cancer cells in the tumor microenvironment may be one strategy used by cancer cells for tumor progression.