GZMB and neoplasm: We observed a high positive correlation between 68Ga-grazytracer tumor uptake values determined via in vivo PET imaging and granzyme B levels quantified by ex vivo Western blotting (Pearson’s r = 0.7168, P < 0.01) and ELISA (Pearson’s r = 0.7337, P < 0.01) (Figure 2, I and J).