Don't preheat oven. Grease and flour a 10 inch tube or Bundt pan. Sift together the all purpose flour and self-rising flour; set aside.
In a large bowl, cream together the margarine, shortening and sugar until light and fluffy. Beat in the eggs one at a time. Alternately beat in the flour mixture and the milk, mixing just until incorporated. Finally, stir in the lemon extract and vanilla.
Pour batter into a 10 inch tube or Bundt pan. Place cake in cool oven and set oven to 350 degrees F (175 degrees C). Bake for 1 hour and 15 minutes, or until toothpick inserted in center comes out clean.