Fig. 3. U266/velR increased CD138^- population. (A) After U266 and U266/velR cells were labeled with anti-human CD138, FACS analysis was performed, to determine CD138 expression of the cell lines. Percentage of CD138^- U266 was represented by the mean ± SEM of 3 independent experiments. (B) CD138⁺ and CD138^- U266 cells were isolated, using MACS. Cell proliferation was measured after CD138⁺ and CD138^- cells were treated with 10 nM bortezomib for 72 h, using CCK-8 cell proliferation kit. Data represented the mean ± SEM of 3 independent experiments.