What’s your favorite George Gershwin tune? One of America’s quintessential composers, Gershwin died of an undiagnosed brain tumor in 1937 at the age of 38 – but not before he put his indelible stamp on the American song. We’ll explore Gershwin’s short but prolific career this hour with Howard Pollack Professor of Music at the University of Houston and author of the new book “George Gershwin: His Life and Work” (University of California Press, 2007).