This past Saturday evening, Mary J. Blige and Jay-Z kicked off their two-month “Heart of the City” tour in Miami, Florida. Joining them at American Airlines Arena for opening night were Kanye West, Young Jeezy and The-Dream, as well as most of the R.O.C. roster. Using the tour as her main promotional tool through the end of April, Blige has released Stay Down as the next single off her recently released platinum-selling album, Growing Pains. The Bryan-Michael Cox-produced selection is a fitting choice as the LP’s third single, considering its theme is dedication and long-lasting support; both topics of discussion on the tour’s unofficial theme song, You’re Welcome. Look for Blige (along with Mr. Carter) in a city near you very soon.