(A) Time course of CCR10 surface expression in HS-5 stroma cells transfected with 25 nM non-target siRNA control (solid histogram) or transfected with 25 nM CCR10 specific siRNA (open histogram, dashed line) relative to isotype control (open histogram, solid line) was determined by flow cytometry and is shown in the histograms. Graphs: Myeloma cells were cocultured with transfected HS-5 stroma cells (non-targeting siRNA (siRNA NT) and CCR10-specific siRNA (siRNA CCR10), respectively) at a ratio of 2:1, and treated for 48 hrs as indicated (bortezomib 5.2 nM, CCL27 7.9 nM). Viability of myeloma cells is presented as percentage of control (n = 4, mean+/−SD; **p < 0.01). (B) Myeloma cells were cocultured with transfected HS-5 cells and treated as above. IL-10 levels of the supernatants were measured by Elisa after 24 hrs. Data are shown as the mean ± SD from 4 independent experiments. **p < 0.01; ***p < 0.001; (C) Viability of myeloma cells cocultured for 48 hrs with HS-5 cells (left graph) or primary fibroblast (PFF) cells (right graphs) and treated with bortezomib (5.2 nM), CCL27 (7.9 nM), and blocking antibodies against IL-10 and IL-10 receptor (both at 2 μg/well), respectively, is shown as mean of at least 3 independent experiments performed in triplicates, +/− SD. *p < 0.05, **p < 0.01, ***p < 0.001.