PREHEAT oven to 350ºF. Beat cake mix, dry pudding mix, water, egg whites and oil in large bowl with electric mixer on low speed until moistened. (Batter will be thick.) Beat on medium speed 2 min. Spoon batter evenly into 24 paper-lined muffin cups.
BAKE 21 to 24 min. or until wooden toothpick inserted in centres comes out clean. Cool in pans 10 min.; remove to wire racks. Cool completely.
MEANWHILE, beat sugar, cream cheese, butter and juice with electric mixer on low speed until well blended. Frost cupcakes.