Activity of thalidomide and CC-4047 on erythroid colony formation and CAFCs. A total of 1.5 × 10³ CD34⁺ cells were cultured in methylcellulose with SCF, IL-3, and hyper–IL-6 and increasing concentrations of thalidomide () or CC-4047 (▪) as indicated. As vehicle control, 0.1% DMSO was used (□). CFU-E was evaluated at day 7 and BFU-E and CFU-GM at day 14. (A) Erythroid colonies (BFU-E + CFU-E) and (B) myeloid colonies (CFU-GM) were calculated as percentage of total colony numbers. (C) Total colony numbers were counted per plate. (A-C) Results are shown as means ± standard deviation from 3 independent experiments. ^*Significant change (P = .05) from control, calculated by ANOVA, followed by the Scheffe method as a post hoc test. (D) Cobblestone area forming cell (CAFC) assay. Frequencies of CD34⁺ cells required to form one cobblestone area under treatment with CC-4047 or thalidomide are shown. Data represent means ± standard error at 16 samples. The open bar indicates control (0.01% DMSO).