CXCL12 and central nervous system cancer: In the brain, dysbiosis and microbiota-associated metabolic products, such as neurotransmitters, SCFAs, and amino acids, can cause changes in the CNS TME, which may be related to tumors.366,370,374–377 It was demonstrated that compound K, a metabolite derived from ginsenoside and biotransformed by the gut microbiota, inhibited the migration of glioma cells, which were stimulated by stromal cell-derived factor-1 (SDF-1).385 SDF-1 has previously been shown to positively regulate the growth and migration of glioma cells.386