For instance, when Liu et al. transfected retroviral vectors containing CAR-CD19, IL-15, and caspase-9 suicide genes into CB-derived NK cells, the results demonstrated a significant prolongation of the survival of Raji lymphoma mice in vivo in addition to significant cytotoxicity against CD19 cell lines and primary leukemia at the in vitro level. Here, CD19 is linked to leukemia.