Moreover, as a positive control for saporin cytotoxicity, we investigated the cytotoxic effects of a saporin-based conjugate (FGF-saporin) directed against the FGF (basic fibroblast growth factor)-receptor on PC3(PSM+) and PC3(PSMA-) prostate cancer cell lines (Supplementary figure 5B). Here, FOLH1 is linked to prostate carcinoma.