KLK4 and neoplasm: The anti-tumor effects associated with KLK4 were also observed in the hind legs, where 16% (four of 24, from twelve mice) of hind legs from mice injected with PC3-PSMA/KLK4 had detectable tumors, in contrast to 50% (12 of 24) with the PC3-PSMA/Vec group (Figure 4F).