Los Ántrax is a large enforcer unit and hit squad for the Sinaloa Cartel, a major crime syndicate based in the Mexican state of Sinaloa. The group was led by the drug lords Jesús Peña (alias "El 20"), José Rodrigo Aréchiga Gamboa (alias "El Chino Ántrax"), René Velázquez Valenzuela (alias "El Sargento Phoenix"), among others, and they are responsible for a number of homicides and for providing armed security services to Ismael El Mayo Zambada. The gang operates in the capital city of Culiacán, Sinaloa, where its members conduct homicides and violent attacks. Los Antrax is the Sinaloa Cartel's largest and deadliest enforcer unit.