CX3CR1 and glioblastoma: However, among genes encoding cytokines and their receptors, we identified lower gene expression values in tissue samples from elderly versus younger patients for interleukin-18 receptor (IL18R1), interleukin-1 receptor (IL1R2), chemokine (C-X-C motif) ligand 6 (CXCL6) and chemokine (C-X-C motif) ligand 13 (CXCL13), whereas the expression of CX3C chemokine receptor 1 (CX3CR1) was higher in glioblastomas of elderly patients (Supplementary Figure 2A).