Transfection with a Cx43 expression construct increased the expression of MMP1 , MMP13 , ADAMTS4 , ADAMTS5 mRNA and MMP activity in HIG82 synovial fibroblasts in vitro. By quantitative real time RT-PCR, transient transfection of HIG82 rabbit synovial fibroblasts with increasing concentrations of a rat Cx43 expressing plasmid (pSFFV-Cx43) dose dependently increased the gene expression of (A) MMP1, MMP13 as well as the rat Gja1 transgene (please note, these primers do not detect the endogenous rabbit Cx43). N = 3. (B) Likewise, the gene expression of the aggrecanases, ADAMTS4 and ADAMTS5, were increased by the overexpression of Cx43. N = 3. (C) Matrix metalloproteinase activity in conditioned media from Cx43 transfected HIG82 cells was increased nearly 2-fold relative to cells transfected with an empty vector. N = 3. Total DNA was kept constant in all wells by the inclusion of the appropriate amount of an empty vector (pSFFV-neo). Data are shown as means ± standard deviations. Asterisks indicate p-value < 0.05 relative to the empty vector (0 μg) control.