PX-41 is an extremely dangerous super-soldier serum developed by the ICPD illegally.
Sometime before the events of Shattered, the ICPD started working on the PX-41 Plan, with the idea of a super-soldier serum in mind. The ICPD started secretly working on a liquid formula, which they called PX-41. The purpose of PX-41 was to create super-soldiers, or super-police officers. When PX-41 was injected in a human it would turn them into giant, strong beasts. However, after asking the United States Government for permission to continue this project, the government denied permission because it was too dangerous. However, under Chief Gleeson's reign, the cops were corrupt, so they continued it anyway without the government knowing, despite what they were told.
Events of ShatteredEdit
During the events of Shattered, The_Underscore learned about the secret PX-41 plan, and that the cops were doing it behind the government's back. Underscore ratted the cops out to the government anonymously. The government, furious that the police initiated this project after they told them not to, sent the Federal and Financial Underworld Bureau to Interface City to secure the area and punish the cops for going against the government.
PX-41 is an orange liquid that the user must drink or inject into them for it to work. The process (seen in Don't Hesitate to Shoot, used on the PX-41 Criminal) is that once the liquid is inside the person, it takes roughly 5 seconds to kick in. Once this happens the victim is transformed into a tall, monstrous super-soldier beast. In the mission, the cops injected a criminal with PX-41 and he turned, and Chief Gleeson forced James Derettas to fight him. After the battle the PX-41 went to the criminal's heart, automatically killing him.