Anti-p97 and HMW-MAA CAR T cells recognized Melur target cells in vitro. P97 CAR induced faster activation and better cytokine production of T cells, even though the HMW-MAA antigen is expressed to a similar extent on the target tumor cells and the HMW-MAA CAR is known to bind to its target with similar affinity as the p97 does. We hypothesize that a difference in the surface mobility of various melanoma associated antigens might have an impact on CAR T cell activation.