PTP-MEG2 mutants affect growth of ECFCs in suspension culture. Two thousand day-5 PV (top) or normal (bottom) ECFCs infected with recombinant retroviruses carrying GFP control, PTP-MEG2, PTP-MEG2(D→A), and PTP-MEG2(C→S) were cultured in the presence of SCF, EPO, or EPO plus SCF. Cells were attached to glass sides by cytospin, and GFP-positive cells were counted under a fluorescence microscope. Data represent mean ± SD of at least 3 independent experiments.