Knock-down of Spi-1 reinitiate erythroid differentiation. (A) Benzidine staining of representative colonies grown in methylcellulose with or without dox for 6 days. The percentage of Spi-1 expression and the percentage of hemoglobinized colonies with dox relative to untreated cells are given. Magnification, × 40. Cells were observed using a Nikon Eclipse TE300 microscope (Nikon, Champigny sur Marne, France) with a 20×/0.45 NA objective lens. Images were acquired with Nikon Coolpix 950 and processed using Adobe Photoshop (Adobe Systems, San Jose, CA) (B) Cytospin smears of A2B and control cells grown during 6 days in methylcellulose with or without dox and stained with May-Grünwald-Giemsa. Images were acquired as in panel A, except a 40×/0.6 NA objective lens was used.