Preheat the oven to 350 degrees F. Spray a 13x9-inch pan with nonstick baking spray.
In a large bowl, whisk together the flour, sugar, baking powder, salt and baking soda.
Use an electric mixer to mix in the eggs, sour cream, butter, lemon zest and lemon juice. On low speed, beat for 1 minute, until blended. Scrape the sides and the bottom of the bowl with a rubber spatula. Beat on medium speed for 1 minute.
Spread the batter evenly into the prepared pan.
Bake for 40 to 45 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs attached. Let the cake cool completely in the pan on a wire rack.
PREPARE THE ICING:
In a medium bowl, whisk together the powdered sugar, sour cream, butter, lemon zest and lemon juice until blended and smooth. Spread the icing over the top of the cooled cake.