CD69 and neoplasm: Considering that tonic signaling from CAR, the spontaneous CAR activation in the absence of tumor antigen stimulation, plays a crucial role in controlling CAR-T efficacy (39), we measured activation markers CD69 and CD25 and found that the MFI of CD25 was significantly higher in the C-3G-B-3E TRuC-T cells than in the B-3G-C-3E and B-3D-C-3E TRuC-T cells (Figures 2D, E).