Presentation of the experimental strategy used to analyze the consequences of reducing RPS19 levels by introducing siRNA in human CD34⁺ cells. Erythroid and granulocytic colonies were scored in semisolid assays. Cell proliferation was determined by counting cells in liquid culture, and differentiation by analyzing cell phenotype by flow cytometry or cytologic analysis. A indicates 50% RPS19 levels; B, less than 50% RPS19 levels; and Dex, dexamethasone. Results are adapted schematically from the original figures in the papers by Flygare et al, page 4627 and Ebert et al, page 4620.