In a large bowl, combine cake mix, 1 egg and oil; stir until crumbly. Set aside 1 cup for topping. Press remaining mixture into an ungreased 13x9-in. baking dish.
Bake at 350° for 15 minutes. In another bowl, beat cream cheese, sugar, lemon juice and remaining egg until fluffy. Spread over cake. Sprinkle with reserved cake mixture. Bake 15 minutes longer. Cool on a wire rack. Store in the refrigerator.