Figure 1.

The chimeric antigen receptor (CAR) structure of four generations. The conventional structure of CAR (second generation) including a single-chain fragment of variable region antibody, a transmembrane domain, a costimulatory molecule and an intracellular signal domain. The CAR of first generation was basically eliminated because its weak effect. In the third generation, there were more than one costimulatory molecules and there added some chemicals or cytokines in the fourth generation.