SPINK1 and neoplasm: The time required for a 3-fold increase in tumor volume was significantly shorter in the case of DU145/SPINK1 (20.8 ± 3.7 days) than DU145/EV (27.8 ± 4.1 days) xenografts (Figure 4E and Table 2), suggesting that DU145/SPINK1 xenografts were more radioresistant than DU145/EV xenografts.