GATA1 expression and erythroid colony formation is decreased in RPS19-deficient hematopoietic progenitor cells. Human CD34⁺ hematopoietic progenitor cells were infected with lentivirus carrying shRNA against RPS19 or Luc control, sorted for GFP⁺ cells after 3 days, and analyzed 3 or 5 days after transduction, as stated for each panel. (A) shRNA knockdown of RPS19 reduces RPS19 mRNA levels by approximately 60% compared with control 5 days after transduction. (B) p21 mRNA expression is upregulated in RPS19-deficient cells 5 days after transduction. (C) GATA1 protein levels decreased in RPS19-deficient fetal liver cells [Scr, scrambled control shRNA; RPS19, RPS19 (sh2)] 3 days after transduction. (D) GATA1 and (E) EPOR mRNA levels decrease in RPS19-deficient cells 5 days after transduction. (F) GATA1 and EPOR expression is decreased in CD71⁺ RPS19-deficient erythroid progenitor cells 5 days after transduction. (G) Erythroid colony formation in methylcellulose is reduced in cells with RPS19 knockdown. (H) Myeloid colony formation is decreased in RPS19-deficient cells. (I) Exogenous expression of GATA1 in RPS19-deficient cord blood cells partially rescues their ability to form erythroid colonies in methylcellulose. Data are representative of 2 independent transduction experiments. *P < .05; **P < .01; ***P < .001.