""Hands up! Don't shoot!" and "I can’t breathe!" became mantras of the growing movement to stem police violence, and the systemic racism at the core of the problem. The phrases began appearing in popular culture, showing the speed and depth with which the movement was growing. Professional athletes in the United States are followed closely by millions of fans. So, when basketball superstar LeBron James of the Cleveland Cavaliers warmed up before a game wearing a T-shirt emblazoned "I Can't Breathe," people noticed."