Lenalidomide-induced changes in megakaryocyte proteins coimmunoprecipitated with cereblon. (A) Experimental design for identifying human megakaryocyte–specific proteins interacting with cereblon. Lysate mixture of human megakaryocytes differentiated from CD34⁺ HSPCs and 293T cells transfected with FLAG-tagged cereblon were incubated with and without 10 μM lenalidomide and subjected to immunoprecipitation with antibody against FLAG. Immunoprecipitates were analyzed by sliver staining and MS. (B) Whole-cell lysates (lanes 1-2) and FLAG-specific immunoprecipitates (lanes 3-4) were subjected to silver staining after SDS–polyacrylamide gel electrophoresis. The proteins were denatured in a nonreduced condition. (C) MS signal intensities of FLAG-specific immunoprecipitates in the presence of dimethyl sulfoxide (DMSO) or 10 μM lenalidomide. Each dot shows the yield of the top 25 proteins abundant in megakaryocyte lysate (supplemental Figure 2) and DDB1 (green dot).