HSPA9 and myelodysplastic syndrome: Increased apoptosis in hematopoietic cells has been observed in various HSPA9 knockdown models, including primary human and mouse hematopoietic cells.[10,16] The known function of HSPA9 to protect cells from a variety of stresses may be partially mediated through its regulation of TP53, and haploinsufficiency may ultimately limit a cell’s ability to appropriately regulate stress states, including MDS.