GFAP and neoplasm: In addition, we observed an up-regulation of an astrocyte marker, glial fibrillary acidic protein (GFAP) expression in the ipsilateral spinal cord (Fig 1F and G), which corresponds to the site of central projections of sensory neurons that innervate the tumor-inoculated femur, suggesting that the presence of tumor in bone induces central sensitization, which is identified by activation of astrocytes in the central nervous system (Ishikawa et al, 2018; Li et al, 2019).