GATA1 downregulation is mediated through activation of p53 and TNF-α. (A) Stabilization of p53 by Nutlin-3 in CD34⁺ hematopoietic progenitor cells leads to dose-dependent upregulation of p21 and (B) TNF-α, as well as (C) downregulation of GATA1. (D) shRNA-mediated knockdown of p53 in RPS19-deficient cord blood cells reduces p21 and (E) TNF-α expression while (F) increasing expression of GATA1 5 days after transduction. (G) Erythroid colony formation is increased in RPS19-deficient CD34⁺ cord blood cells cotransduced with p53 shRNA compared with Luc control shRNA. Data are representative of 2 independent experiments. *P < .05; **P < .01; ***P < .001.