MEXICO CITY and LONDON -- Roadside banners prohibiting the production and sale of fentanyl have appeared in Mexico's northern state of Sinaloa, where the eponymous drug cartel is based. The machine-printed banners were purportedly signed by a faction of the Sinaloa cartel led by the sons of jailed Mexican drug lord Joaquin "El Chapo" Guzman. The sons are known as "Los Chapitos" after their infamous father, who was extradited