Mix together the sugar, sour cream, eggs, melted butter, mashed banana and vanilla in a large bowl. ?In a separate bowl, combine the flour, cinnamon, salt, baking soda and baking powder. Gradually mix the dry ingredients in with the wet ingredients until well combined and smooth.?Pour batter into prepared pan, and bake at 375*F for about 30 minutes (check after 25 minutes). Bake until a toothpick inserted in the center comes out clean, or with a few moist crumbs, but no wet batter.?Cool (in pan) on wire rack.