Testing CD137-CD3ζ, CD28-CD3ζ, and CD3ζ-containing constructs in NK-92 cells demonstrated that CD137-CD3ζ-CAR-NKs were less effective in killing CD19-positive B-ALL blasts and secreting cytokines, including granulocyte–macrophage colony-stimulating factor (GM-CSF) and IFN-γ compared to the other two constructs [49]. Here, TNFRSF9 is linked to acute lymphoblastic leukemia.