Alteration of PTP-MEG2 expression and the effects on erythroid colony formation. Day-5 PV ECFCs were infected with recombinant retroviruses carrying vector control, PTP-MEG2, PTP-MEG2(D→A), and PTP-MEG2(C→S). Cells were collected 3 days later for immunofluorescent cell staining with anti-PTP-MEG2 (A) and for erythroid colony-forming assays (B). Data show fluorescent anti-PTP-MEG2 staining, GFP fluorescence, and bright field photo images. Note the exposure time for antibody staining of the vector control was longer. Original magnifications, × 1000 (A) and × 40 (B).