IL18 and neoplasm: To evaluate the neuronal mechanism of NFAT1/IL‐18 in the development of pain hypersensitivity induced by tumor inoculation, we evaluated the change in the expression of p‐NR2B, p‐CaMKII, and p‐CREB in the spinal dorsal horn by using spinal blockade of NFAT1 or IL‐18.