Inhibition of miR-21 stimulates erythropoiesis in MDS. MDS bone marrow–derived MNCs from 5 patients with MDS (A) and 3 controls (B) were plated in methylcellulose and cytokines in the presence and absence of miR-21 inhibitor (50 nM). Colonies were scored at Day 14 and results were expressed as means ± SEM of independent experiments.