A 49-year-old man was fatally stabbed Friday night during an argument on a CTA bus on the West Side in the West Garfield Park neighborhood, Chicago police said. Shortly after 8 p.m., the victim was involved in an argument with a woman on a CTA bus in the 200 block of South Cicero Avenue. The woman pulled out a knife and stabbed the victim in the chest before fleeing the scene, police said. The victim was taken to Mount Sinai Hospital where he was pronounced dead. No one was in custody and detectives are investigating.