CXCL12 and cancer: Class I showed over-expression in majority of cancer types such as tubulin alpha 1b (TUBA1B) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Table 2), class II represented down-expression in most of HCs such as aspartoacylase (ASPA) and chemokine (C-X-C motif) ligand 12 (CXCL12) (Table 2), while the rests (Class III) showed a mixed expression patterns in different types of cancers such as protein kinase (cAMP-dependent, catalytic) inhibitor beta (PKIB) (Table 3).