RNA interference functions in CD34⁺ cells. Cultured erythroblasts were transfected with a plasmid expressing GFP and either a control RNA (A-B) or an siRNA to GFP (C-D). Laser scanning confocal micrographs of cells showing fluorescent (A,C) or phase contrast (B,D) images of the same cells; scale bar is 40 μm. (E) FACS analysis at day 3 to measure the mean fluorescence of GFP expression in the GFP-positive populations from cells transfected at day 0 with pEGFP (lane 1), pEGFP plus an unrelated siRNA (lane 2), or pEGFP plus GFP-specific siRNA (lane 3) or of the total population of mock transfected cells (lane 4).