SHP2 knockdown in CD34⁺ cells results in significantly reduced progenitor survival. (A) CD34⁺DsRED⁺ cells were cultured in SFM with low, physiologic concentrations of GFs for 3 days and analyzed for apoptosis by labeling with annexin V and DAPI. Data are mean ± SEM of 3 experiments. *P < .05, sh-Shp2-1 and **P < .01 for sh-Shp2-2 compared with sh-Ctrla. (B) The effect of GF withdrawal for 24 hours on apoptosis of CD34⁺DsRED⁺ cells was evaluated. Data are mean ± SEM of 3 experiments. **P < .01 with or without GF withdrawal. (C) CD34⁺DsRED⁺ cells cultured in high concentrations of GFs. SFM were analyzed for apoptosis. Data are mean ± SEM of 4 experiments. *P < .05, sh-Shp2-1 and sh-Shp2-2 compared with sh-Ctrla.