PTGS2 and acute myeloid leukemia: One such study demonstrated that mesenchymal stromal cells (MSCs) from AML subjects or normal MSCs with an increased expression of cyclooxygenase-2 (COX2) stimulated the growth of co-cultured hematopoietic stem and progenitor cells (HSPCs), which can be avoided by use of COX2 knockdown or TM30089, an antagonist of the PGD2 receptor CRTH2.