PTEN and myelodysplastic syndrome with single lineage dysplasia: In addition, we observed a significant increase in the expression of the phosphatases PTEN, INPP4B, and SHIP1 in MDS CD34+ cells compared to healthy CD34+ cells, particularly in the refractory anemia (RA) with excess blasts (RAEB) subset of high-risk MDS cases (Fig. 1A).