CD19 and acute lymphoblastic leukemia: Using CRISPR/CAS9 on the CD19-specific CAR-targeted T-cell receptor α constant (TRAC) site not only results in uniform CAR expression in human peripheral blood T lymphocytes but also enhances the activities of T cells, which are much better than those CAR-T cells conventionally produce in acute lymphoblastic leukemia (ALL) mouse models [56,81] (Figure 3).