On Wednesday, precisely one week after he won three Grammy Awards, Eminem, 28, was snubbed at the Soul Train Music Awards, for the past 15 years a prominent showcase for popular African-American culture. Eminem's "The Marshall Mathers LP" lost the album of the year award to his mentor Dr. Dre's "Dr. Dre -- 2001." His clip for "Stan" (the song that Eminem and Elton John sang together at the Grammys) was shut out for best video by rapper Mystikal's "Shake Ya Ass." Soul Train nominees and winners are determined by a selective poll of radio station programmers, recording artists and music retail personnel. Eminem did not attend the Soul Train event, which was taped at L.A.'s Shrine Auditorium and will be broadcast nationally on March 3.