Protein Phosphatase (PP) activators are molecules, like the natural PTPA (Phosphotyrosyl Phosphatase Activator) or synthetic compounds (e.g., PPA24, P5SAs), that increase the activity of phosphatases (enzymes removing phosphate groups from proteins) to regulate cell signaling, metabolism, and cell cycles, often acting as potential anti-cancer agents by restoring function to suppressed tumor-suppressing phosphatases like PP2A or modifying others like PP5. Used as building blocks of Multi-target drug ligand MTDL