Preheat oven to 350 degrees F (175 degrees C). Grease and flour a 10 inch tube pan. In a small bowl, beat cream cheese, confectioners' sugar and lemon juice until smooth; set aside. In a medium bowl, stir together flour, baking powder, baking soda, and salt; set aside.
In a large bowl, cream together the butter and 1 cup white sugar until light and fluffy. Beat in the eggs one at a time, then stir in the vanilla. Beat in the flour mixture alternately with the sour cream, mixing just until incorporated. Pour half of batter into prepared pan. Spoon cream cheese mixture on top of batter to within 1/2 inch of pan edge. Spoon remaining batter over filling, spreading to pan edge. In a small bowl, combine chopped nuts, 2 tablespoons white sugar and 1/2 teaspoon cinnamon. Sprinkle over batter in pan.
Bake in the preheated oven for 40 minutes, or until a toothpick inserted into the center of the cake comes out clean. Let cool in pan for 10 minutes, then turn out onto a serving plate and serve warm.
