Fig. 5.

Up-regulated MMP-9 is not uniquely responsible for CD73 shedding. LPS and TNF-α, individually or in combination, on regulating MMP-9 expression extracellular activity were detected by qPCR (a) and a MMP-9 Biotrak activity assay (b). Effect of exogenous MMP-9 on CD73 shedding in Mmp9^−/− RPE cells received LPS/TNF-α treatment or not (c). a qPCR results of Mmp-9 expression in RPE cells (n = 6). b Amount of active MMP-9 in the medium of RPE cells. c Effect of exogenous recombinant MMP-9 on regulating CD73 shedding; a representative flow cytometry result (left column) and statistical analysis of FACS determined percentage of CD73 positive cells (right column)