Question: Juan García Ábrego was the nephew of the founder of what drug gang?

Context paragraphs:
Juan Carlos García Sancho: Juan Carlos García Sancho Orozco (born November 10, 1994 in Tepic, Nayarit), known as Juan García Sancho, is a professional Mexican footballer who currently plays for Cruz Azul.

Juan García Hortelano: Juan García Hortelano (1928–1992) was a Spanish writer.  He was born in Madrid on Valentine's Day 1928.  His father was a doctor.  When the Spanish Civil War broke out, he was sent with his siblings to Cuenca, only returning to Madrid in 1937 where he lived with his maternal grandparents.  The libraries at school and home turned him into an avid reader.  Following the war, he entered college in 1941, later studying law at Madrid University.  He joined the Civil Service in 1953.  Throughout his life, he dedicated himself to writing with fervour and discipline without abandoning his administrative job in Madrid.  He cultivated friendships with writers and intellectuals of his generation: Juan Benet, Carlos Barral, Jaime Gil de Biedma, Juan Marsé and Ángel González.

Aggi Crew: The Aggi Crew were a criminal drug gang based in the St Paul's district of Bristol.  The name of the gang was taken from the surnames of the founding gang members.  The gang dominated the city's drug market throughout most of the 1990s, until in 1998 six gang members were jailed after being caught with more than a £1 million worth of crack cocaine.

Osiel Cárdenas Guillén: Osiel Cárdenas Guillén (born May 18, 1967) is a former Mexican drug lord and the former leader of the Gulf Cartel (Spanish: "Cártel del Golfo" ) and Los Zetas.  Originally a mechanic in Matamoros, Tamaulipas, where he was born, he entered the Gulf Cartel by helping Juan García Abrego, the capo at the time; when García Ábrego was arrested in 1996, some infighting erupted within the cartel.  Osiel Cárdenas eventually took control by killing his friend and contender Salvador Gómez, earning Cárdenas the nickname ""El Mata Amigos"" (The Friend-Killer).

Juan García Ábrego: Juan García Ábrego (born September 13, 1944) is a former Mexican drug lord who started out his criminal career under the tutelage of his uncle Juan Nepomuceno Guerra, who is reported to be the former head of a criminal dynasty along the U.S.-Mexico border now called the Gulf Cartel.

Christopher Coke: Christopher Michael Coke, also known as Dudus (born 13 March 1969), is a Jamaican drug lord and the leader of the Shower Posse, a violent drug gang started by his father Lester Coke in Jamaica, which exported "large quantities" of marijuana and cocaine into the United States.

Juanín García: Juan García Lorenzana, known as Juanín García, (born 28 August 1977, in León) is a Spanish handball player.  He currently plays for Barcelona, with whom he won the Champions League in 2011 in the finale against Ciudad Real.

María de los Ángeles Pineda Villa: María de los Ángeles Pineda Villa is the former first lady of Iguala, a city in Guerrero, Mexico.  Pineda Villa and her husband, José Luis Abarca Velázquez were accused by Attorney General of Mexico Jesús Murillo Karam of the "probable masterminds" behind the 2014 Iguala mass kidnapping and disappearance of 43 students from the Ayotzinapa Rural Teachers' College.  Pineda Villa and her husband fled hours after the reported abductions and were arrested by federal authorities on November 4, 2014.  The prosecution's investigation indicates that Mayor Abarca ordered local police to stop the students from protesting a political event and speech Pineda Villa was scheduled to hold.  The police allegedly attacked the students' buses when they entered Iguala and then delivered them to members of the local drug gang, Guerreros Unidos.  Along with her familial ties to the Sinaloa Cartel and Beltrán-Leyva Cartel, confessions by detained gang members and police officers have revealed Pineda Villa as the "principle operator" of the Guerreros Unidos.

Altamira prison brawl: The Altamira prison brawl was a deadly fight that occurred on 4 January 2012 in Altamira, Tamaulipas, Mexico.  Officials from the state of Tamaulipas confirmed that 31 people were killed, with another thirteen injured.  The fight started after a drug gang burst into a section of the prison where they were banned from, attacking their rival gang housed there, triggering the fight.  During the altercation, the inmates used several kinds of white arms to kill their opponents.  The prisoners also used sticks and knives to massacre the members of the rival gang.

Juan Nepomuceno Guerra: Juan Nepomuceno Guerra Cárdenas (July 18, 1915 – July 12, 2001) was a Mexican crime lord, bootlegger, businessman and smuggler who founded the Gulf Cartel, a drug trafficking organization.  He is often considered the "godfather" of U.S-Mexico border cartels.

Supporting paragraphs: Juan García Ábrego Juan Nepomuceno Guerra
Answer: Gulf Cartel