PTGER2 and central nervous system cancer: The 340 SRGs in different histologic grade gliomas were integrated into the univariate Cox analysis to identified key SRGs and we found that CCL7, CXCL6, SELE, C2CD4A, GPR141, TNFSF14, CCR2, GPR171, PTGER2 and VGLL3 were associated with histologic grade (Figure 5E).