Obagi Nu-Derm Transformation System accelerates cellular turnover for skin with moderate to severe sun damage. As you age and your skin incurs the abuse of daily living (such as sun, stress, pollution), the cell turnover rate slows down. This means that the new cells take longer to form and reach the top. The old cells accumulate and stay on the surface longer. As the stratum corneum thickens and the area of new cells shrink, skin becomes less healthy.