Similar spleen erythroblast maturation between ERK1^+/+ and ERK1^−/− mice. May-Grünwald-Giemsa–stained cytospin preparations of sorted ProE, Ery.A, Ery.B, and Ery.C subsets. Representative fields of cells are shown for each region. The photographs were taken at an original magnification of ×400 with a Leica DXC 950P microscope and TRiBVN ICS image-acquisition software.