smad2 is activated in MDS. Bone marrow (BM) biopsies from patients with MDS and controls with non-MDS causes of cytopenias were fixed and immunostained with antibody against phospho-smad2 (A). Histologic examination reveals more intense staining in MDS samples. Eight representative samples of MDS and controls are shown in panel A. The quantification of p-smad2 staining was analyzed by counting the total number of positively stained cells (B) and by measuring intensity of the positively stained cells (C) in 5 hot fields (which is defined as area of high density of p-p38 staining) and aided by Image Pro Plus (Nikon, 400×). Two-tailed t test shows significantly higher smad2 activation/field in MDS samples. Differences in smad2 expression were also evaluated in normalized meta-analysis of MDS CD34⁺ (69 cases)– and normal CD34⁺ (57 cases)–cell–derived gene expression microarray studies. Smad2 gene expression was significantly up-regulated in low-grade MDS bone marrow CD34⁺ cells (2-tailed t test) (D). Error bars represent SEM.