FOLH1 and cancer: The objective of this study was to develop a multifunctional theranostic approach that combines a cytotoxic drug (MMAE), a photosensitizer (IR700) and a low molecular weight PSMA targeting ligand (PSMA-1-Cys-C6-Lys) into a single molecule, PSMA-1-MMAE-IR700, selectively and simultaneously delivering both chemotherapeutic drugs and photosensitizers to cancer cells (Figures 1 and 2A).