LGALS9 and hematopoietic and lymphoid cell neoplasm: Several of these negative regulatory mechanisms appear to be shared between solid and hematological cancers, including expression of negative costimulatory ligands, such as programed death-ligand 1 (PD-L1) and galectin 9 (Gal-9) on AML cells, and induced expansion of immunoregulatory cells, such as regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) (14–18).