1. Preheat oven to 350°. Beat butter at medium speed with an electric mixer until creamy; gradually add sugar, beating 4 to 5 minutes or until light and fluffy. Add eggs, 1 at a time, beating until blended after each addition. Beat in lemon juice and vanilla.
2. Stir together flour and next 3 ingredients; add flour mixture to butter mixture alternately with buttermilk, beginning and ending with flour mixture. Beat at low speed just until blended. Stir in strawberries.
3. Grease (with shortening) and flour a 13- x 9-inch pan; line with parchment paper, allowing 2 to 3 inches to extend over long sides. Lightly grease paper with cooking spray. Spread batter in prepared pan.
4. Bake at 350° for 30 to 40 minutes or until a wooden pick inserted in center comes out clean. Cool in pan on a wire rack 30 minutes. Lift cake from pan, using parchment paper sides as handles. Invert cake onto wire rack; gently remove parchment paper. Cool completely (about 1 hour). Spread Strawberry Frosting on top and sides of cake.