SFRP4 and central nervous system cancer: By contrast, among the genes that showed the highest upregulation in our array we found angiopoietin-like 1 (ANGPTL1), a well-known anti-angiogenic gene normally reduced in GBM [41], the secreted frizzled-related protein 4 (SFRP4), a Wnt antagonist also reduced in high grade GBM that helps eliminate glioma cells by making them more vulnerable to chemotherapy [42], RARRES3 which is a tumor suppressor gene also inhibited in advance cancers [43], or Asporin (ASPN), a small leucine-rich repeat proteoglycan, identified as a growth suppressor of GBM cells in vitro and in vivo [44].