KLK3 and neoplasm: Serum PSA, a surrogate marker for total body prostate tumor cell burden [25], was used to confirm the anti-tumor effects and was significantly lower ( p<0.001 vs. dual control; One way ANOVA and Bonferroni's post-hoc analysis) in 225Ac-E4G10 treated animals as compared to the controls (Fig. 2D).