MDK and central nervous system cancer: In a comparison of isocitrate dehydrogenase (IDH) wild-type to IDH mutant gliomas, one study found that midkine (a neuroinflammatory cytokine that promotes macrophage polarization to an M2 phenotype) was preferentially upregulated in CD45+ myeloid cells of IDH wild-type gliomas as compared to IDH mutated gliomas (6).