In vitro stem and progenitor cell function is inhibited by constitutive expression of GATA-2. (A) Transduced CD34⁺CD38⁻ cells show a GATA-2–specific loss of LTC-IC activity in vitro. Mean frequency (± SEM) of LTC-ICs in the transduced populations is shown for 5 independent experiments. (B) Data from 1 representative experiment shown in panel A is presented as the cell number plated per well versus the number of wells that did not contain an LTC-IC. (C) LTC-IC frequency in transduced CB CD34⁺CD38⁻ cells sorted by GFP expression level. A single representative experiment is shown. (D) Same data as in panel C, plotted as the cell number plated per well versus the number of wells that did not contain an LTC-IC. (E) CFC frequency in transduced CB CD34⁺ cells. (n = 4; error bars indicate SEM). (F) Same data as in panel E, plotted for colony type distribution. Mean proportions of total colonies of myeloid (G/M/GM), erythroid (E), or mixed (GEMM) types are shown from 4 independent experiments. G indicates granulocyte; M, macrophage; GM, granulocyte/macrophage; GEMM, granulocyte/erythroid/monocyte/macrophage; n = 4; error bars indicate SEM. (G) Photomicrograph of representative erythroid colonies from transduced CB CD34⁺ cells (Nikon SMZ1500, 1× objective, Nikon DXM1200F camera using ACT-1 v.2.12; Nikon UK Limited, Kingston Upon Thames, United Kingdom). (H) Total CFC colony number in transduced CB CD34⁺ cells sorted by GFP expression level. A single representative experiment is shown. (I) Enforced expression of GATA-2 in CD34⁺CD38⁻ cells similarly inhibits colony formation but (J) here leads to a modest increase in erythroid colony output; n = 4; error bars indicate SEM.