James Cagney helped jump-start the gangster genre as The Public Enemy. Outcries against movies that glorified underworld criminals put Cagney on the side of the law in 'G' Men.James Cagney helped jump-start the gangster genre as The Public Enemy. Outcries against movies that glorified underworld criminals put Cagney on the side of the law in 'G' Men.James Cagney helped jump-start the gangster genre as The Public Enemy. Outcries against movies that glorified underworld criminals put Cagney on the side of the law in 'G' Men.