Efficient and rapid killing of B cell tumors by CAR T cells in the bone marrow (example 1). C57BL/6 mice were sublethally irradiated and injected with Eμ-myc-DEVD tumor cells 7 d before treating them with GFP+ CAR T cells. Mice were subjected to intravital bone marrow imaging 40 h after CAR T cell transfer. Live tumor cells appear in gray, apoptotic tumor cells in blue, and T cells in green. Squares highlight tumor cell apoptosis during direct contacts with CAR T cells. Scale bar represents 20 μm. Total duration = 64 min.