To ensure rapid killing of the cancer cell, the chimeric antigen receptor is further modified to contain the activation domains of both CD3ζ and another stimulatory receptor (i.e., CD28, 4-1BB, ICOS, OX40, etc.)Equipped with these enhancements, CAR T cells have recently demonstrated the ability to eradicate cancers that have historically been resistant to standard therapies1,2. Here, CD28 is linked to cancer.