The activation of MAPK pathways in spinal cord and subsequent production of proinflammatory cytokines in glial cells contribute to the development of spinal central sensitization, the basic mechanism underlying bone cancer pain (BCP). Our previous study showed that spinal CXCL12 from astrocytes mediates BCP generation by binding to CXCR4 in both astrocyters and microglia. Here, we verified that CXCL12/CXCR4 signaling contributed to BCP through a MAPK-mediated mechanism. In na€ ıve rats, a single intrathecal administration of CXCL12 considerably induced pain hyperalgesia and phosphorylation expression of spinal MAPK members (including extracellular signal-regulated kinase, p38, and c-Jun N-terminal kinase), which could be partially prevented by pre-treatment with CXCR4 inhibitor AMD3100. This CXCL12-induced hyperalgesia was also reduced by MAPK inhibitors. In bone cancer rats, tumor cell inoculation into the tibial cavity caused prominent and persistent pain hyperalgesia, and associated with up-regulation of CXCL12 and CXCR4, activation of glial cells, phosphorylation of MAPKs, and production of proinflammatory cytokines in the spinal cord. These tumor cell inoculation-induced behavioral and neurochemical alterations were all suppressed by blocking CXCL12/CXCR4 signaling or MAPK pathways. Taken together, these results demonstrate that spinal MAPK pathways mediated CXCL12/CXCR4-induced pain hypersensitivity in bone cancer rats, which could be druggable targets for alleviating BCP and glia-derived neuroinflammation. Keywords: astrocytes, bone cancer pain, chemokine, mitogenactivated protein kinase, microglia, neuroinflammation. Bone cancer pain (BCP) caused by primary tumors or bone metastases is the most common source of moderate and severe cancer pain, which not only makes patients less confident to receive therapeutic plan but also discourages tumor-burdened people from desiring to live (Knopp et al. 2011). With effective treatment strategies depending on a better understanding of BCP, intensive studies of underlying pathogenic mechanisms of BCP and development of novel analgesic targets are highly anticipated in the basic and clinical research communities.Following local inoculation of primary or metastatic bone tumor in the bone microenvironment, cellular and neurochemical alterations take place abundantly in the spinal cord, triggering hyperalgesic behaviors (Medhurst et al. 2002). In this complex pathophysiologic process, glial cells (especially astrocytes and microglia) react and release various proinflammatory cytokines, including tumor necrosis factor a (TNF-a), interleukin 1b (IL-1b) and IL-6, which enhance central sensitization and thus evoking pain hypersensitivity (Falk and Dickenson 2014). Indeed, inhibiting functional activation of astrocytes and microglia at the spinal level is sufficient to suppress BCP and these glia-derived mediators Moreover, numerous studies have shown that all three MAPK members are prone to be phosphorylated following the activation of certain GPCRs, especially che...