Drain cherries and reserve two tablespoons of liquid. Chop cherries; set aside. Preheat oven to 350. Prepared a 9"x5" loaf pan with cooking spray; set aside. In a medium sized bowl, combine flour, baking powder, salt, and baking soda; set aside. In a mixing bowl, combine margarine, brown sugar, eggs, and reserved liquid from cherries. Mix until combined. Add flour mixture, bananas, cherries, and nuts. Mix until all is moistened. Pour into prepared loaf pan. Bake for one hour, or until toothpick inserted in center comes out clean.