Microglia-derived cytokines and chemokines, particularly PDGFB, EGF, SDF-1α, IL-6, and IL-8, activate Pyk2, but only PDGFB, EGF, SDF-1α and IL-6 promote Pyk2-related glioma cell invasion and proliferation. This evidence concerns the gene CXCL12 and central nervous system cancer.