CD34 and myelodysplastic syndrome: In this study, we found that HSPA9/mortalin inhibition disrupts erythroid maturation dependent on TP53 using human CD34+ hematopoietic progenitor cells, consistent with the report by Caceres et al. 43that TP53 suppression promotes erythropoiesis in del(5q) MDS. Collectively, our results suggest that the increased apoptosis and reduced erythroid maturation observed in del(5a)-associated MDS is TP53-dependent.