Serum analysis revealed up regulation of various cytokines along with PGE2 which may be the underlying factor contributing to increased metastasis in arthritic mice. A: A graphical representation of the up regulated cytokines in the bone and lung lysate (*p < 0.05, **p < 0.01, ***p < 0.001). The Ray Biotech cytokine array kit was utilized for this experiment and average of n = 4 mice. B: Increased circulating PGE2 in the arthritic versus the non-arthritic PyV MT mice (*p < 0.01 versus PyV MT mice), n = 10 mice per group. A specific ELISA was used for this experiment. The statistical differences between groups are shown with horizontal bars. We have compared the statistical differences between 1) C57Bl/6 with C57Bl/6 + CII at 9 and 18 weeks; and 2) PyV MT with PyV MT + CII at 9 and 18 weeks.