ACKR2 and central nervous system cancer: Mouse upstream regulators inhibited by metronomic CPA in both tumor models include: CSF2 (GM-CSF), which induces differentiation of brain macrophages into M1 anti-tumor macrophages [64], but has also been shown to be neuroprotective [65], and perhaps its down-regulation is important for tumor ablation in these brain tumor models; TRIM24, which promotes glioma progression and enhances chemoresistance [66]; DNASE2; G-protein coupled receptors PTGER2 and ACKR2; SOCS1, an inhibitor of cytokine signaling; the oncomir mir-21; growth factor TGFB; and the oncogene Myc.