p38 inhibitor SCIO-469 can decrease apoptosis in MDS CD34⁺ progenitors. BM mononuclear cells from patients with MDS were cultured in the presence and absence of 500 nM SCIO-469 for 48 hours. Apoptosis in gated population of CD34⁺ cells was determined by Annexin V staining. Comparison of dot plots from 5 independent experiments shows a decrease in the percentage of Annexin V–positive CD34⁺ cells in samples treated with SCIO-469 (A). MDS CD34⁺ progenitors from 5 patients show significantly greater viability and decreased apoptosis after 48 hours of treatment with SCIO-469 (paired 2-tailed t test). Results are presented as means ± SEMs (B).