Muhammad X is the self-proclaimed protector of Harlem NY, using his ability to alter density and gravity to protect the community. When Superman runs into him, Muhammad stares at him, accusing him of ignoring Harlem and especially the black community. This causes the Man of Steel to question his understanding of race relations and leads to his seeking advice from his friends and colleagues such as Lois Lane and Natasha Irons.
Natasha names a few black superheroes Superman has never heard of, but are apparently well known in the black community, such as Rush & Silence, Stoneyard and Underground.
Superman encounters Muhammad X a second time, telling X that he can't change the color of his skin... but what he his trying to do is something far more difficult... to be a human being. And hopefully, someday, they will see each other only in that way." Superman flies off, to which Muhammad replies to himself "Yeah, well... I guess that's how you sleep at night."