Howie B Leaves PopMart

November 4 [16:00 EDT] -- Noted DJ Howie B has left his high-profile spot on the U2 PopMart tour, but no one is saying why.

Howie, who co-produced U2's latest effort, "Pop," has been spinning on the band's tour since it kicked off in Las Vegas in April, but Howie (a/k/a Howard Bernstein) turned in his last performance with the tour on Tuesday, October 27 in Toronto.

Neither the U2 camp nor the Howie B camp would comment on why he has left the tour, but reports have cited everything from an ailing family member to brushes with the law.

Meanwhile, the suddenly Howie-less PopMart tour will roll into St. Louis on Saturday.