CXCR4 and neoplasm: Hypoxic conditions in the TME stimulate anaerobic glycolysis, leading to acidification of the extracellular matrix (ECM), which can promote conversion of normal MSCs (CD105+CD73+CD90+CD29+CD44+CD79a-CD11b-CD19- or CD45-CD34-CD14- HLA-DR-) [13] in tumor cells through activation of the NF-kB pathway [358] and expression of CCL5, CXCL5, CXCL1, IL-6, IL-8, and CXCR4.