CD19 and CD20 specific CARs against B cell malignancies (39–41, 53, 54), and CARs targeting CD33 on leukemia cells (38), CS1 and CD138 on myeloma cells (24, 48, 55), GD2 on neuroblastoma cells (23, 56), Her2/Neu and erbB2 on breast cancer cells (22, 35), carcinoembryonic antigen (CEA) on colon cancers (36), EpCAM on epithelial tumors (29), GPA7 on melanoma (59), NKG2D ligand on leukemia and solid tumors, and TRAIL-R1 on various tumor targets (58) have all been shown to have the capacity to redirect NK cell cytotoxicity against their target antigens. Here, CD33 is linked to leukemia.