Fourth, appropriate PET radiopharmaceuticals need to be selected for tumor imaging (FDG or Ga-68-FAPI (fibroblast activating protein inhibitor) targeting cancer associated fibroblasts) and inflammation imaging (FDG or Ga-68-Pentixafor targeting chemokine signals (CXCL12/CXCR4 pathway), respectively. The gene discussed is CXCL12; the disease is cancer.