Expression of cyclin E (left histogram) and p27 (right histogram) among phase II and phase III plus IV cells isolated from sequential cytokine stimulation of G0CD34+ cells in a two-dimensional tracking experiment. Cells were sorted based on their PKH2 and PKH26 fluorescence as defined in Fig 6 from cultures receiving IL-3 as a primary stimulus and SCF or FL as a secondary stimulus. Phase II cells were those shown in Figs 5, 6, and 7 as green events, and phases III plus IV were those shown as red and blue events, respectively. Cells belonging to Phases III and IV were collected together. Cells were stained for cyclin E and p27 as described in Materials and Methods. Each histogram is an overlay of three separate files derived from the analysis of isotype staining (- - - - -), phase II cells (─) and phase III plus IV cells (━). Positive values for every marker, obtained after background subtraction, are indicated. Similar data were obtained in two other experiments.
