Majority of MEPs are in the CD38mid fraction. (A) Sorting strategy used to evaluate MPL+ and MPL− cells within CD38 negative, low, mid, and high subsets of Lin−CD34+ MPB cells followed by exclusion of FLT3+ and CD45RA+ cells. (B) Dual Mk/E and (C) methylcellulose colony assay results. Results are presented as average + SD from 3 independent experiments.