Beat first 5 ingredients in large bowl with mixer until blended. Stir in poppy seed.
Pour into greased and floured 12-cup fluted tube pan or 10-inch tube pan.
Bake 50 min. to 1 hour or until toothpick inserted near center comes out clean. Cool cake in pan 10 min. Loosen cake from sides of pan with knife. Invert cake onto wire rack; gently remove pan. Cool cake completely.
Beat cream cheese spread and butter in medium bowl with mixer until blended.
Add lemon juice; mix well. Gradually beat in sugar.