Similar intracellular Granzyme B levels in mock and CAR T cells post-tumor co-culture likely reflect basal levels and potential non-specific activation in mock cells, coupled with a snapshot view that doesn't capture the potentially superior and faster degranulation, targeted granule release, or other cytotoxic mechanisms characteristic of functional CAR T cells. Further functional assays and kinetic studies are needed to fully elucidate the differential cytotoxic potential.