Microglial activation and proinflammatory cytokine expression increases in the bone cancer pain model. Real-time quantitative RT-PCR analyses of the temporal expression of microglial activation markers (CD11b, CD14) and proinflammatory cytokines (IL-6, IL-1β, TNF-α, and INF-β) mRNA in rat lumbar spinal cord. The mRNA expression levels of CD11b and CD14 significantly increased in the bone cancer pain group at six days AI and 12 days AI (n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 0.98). CD11b mRNA expression was also higher at 18 days AI (P < 0.05). The bone cancer pain group also showed significant up-regulation IL-6, IL-1β, TNF-α, and INF-β mRNA relative to the normal and sham group(n = 4, ANOVA1w, P < 0.01, post hoc Dunnett testing, df = 3, F = 1.11), starting at day six after inoculation for IL-1β and TNF-α (P < 0.05), and at day 12 after inoculation for IL-6 and INF-β (P < 0.01). Values are presented as mean ± SEM. *P < 0.05, **P < 0.01 vs. normal group; ▲ P < 0.05, ▲▲ P < 0.01 vs. sham group; #P < 0.05, ##P < 0.01 vs. 6 days AI; ◆P < 0.05, ◆◆P < 0.01 vs. 12 days AI.