Ex vivo processing of pro-BMP10 by the PCs and their derivatives, and inhibition by D6R and RVKR-cmk. A, Western blot (WB) analysis of 20-h conditioned medium from CHO-FD11 cells co-transfected with (ProtC)-BMP10 and either an empty vector or furin, sFurin, PACE4, PC5/6, or PC5/6-ΔC. As indicated, the conditioned medium was collected after no treatment (−), or treatment (+) with either the cell permeable convertase inhibitor RVKR-cmk (25 μm) or the cell surface convertase inhibitor D6R (10 μm). For each condition, the average % of pro-BMP10 cleavage and corresponding S.D. values from three to four independent experiments are shown as a bar graph. B, Western blot analyses of 20-h conditioned medium from HEK293 cells (left) or COS-1 cells (right) transiently expressing (ProtC)-BMP10 or no protein (vector) and collected after no treatment (dimethyl sulfoxide, DMSO) or treatment with either the cell surface convertase inhibitor D6R (10 or 20 μm) or the cell permeable convertase inhibitor RVKR-cmk (25 or 50 μm). These data are representative of at least two independent experiments.