Retroviral μGATA-1 expression rescues MDS erythroid differentiation. MDS (n = 5) and controls (n = 2) progenitors are transduced with empty, wtGATA-1, or μGATA-1 vectors and analyzed at day 14. (A) Apoptosis and cell mortality. Flow cytometry for apoptosis with annexin V (left panel) and mortality as Trypan blue⁺ cells (right panel). (B) Quantification of GYPA and HBB transcripts. RT-qPCR in MDS (n = 3) and controls (n = 2) erythroblasts normalized to HPRT. Ratios of mean normalized relative quantity ± SE between wtGATA-1 and μGATA-1–transduced cells to empty vector-transduced cells. (C) GPA expression and hemoglobin synthesis. GPA expression (left panel) expressed as mean percentages ± SE of GFP⁺ cells. Benzidin labeling (right panel) for hemoglobin synthesis measurement as percentages of positive cells. (D) Erythroblast differentiation. Percentage of differentiated polychromatophilic and acidophilic erythroblasts on MGG-stained cytospins (right panel; *P < .05). Representative microphotographs are shown.