Lung cancer is the leading cause of cancer-related death world wide. To combat this, lung cancer prevention trials were conducted in western countries but they were not successful for various reasons. Curcumin, isolated from the plant Curcuma longa (Linn), has been investigated as a promising cancer preventive. However, the exact mechanisms of action of curcumin have not yet been clearly elucidated. We studied the relationship between the expression of GADD45 and GADD153 and apoptotic induction in human lung cancer cells PC-9 and the results suggest that the up-regulation of GADD45 and GADD153 by curcumin is a prime mechanism in the anticancer activity of curcumin. Although curcumin is widely investigated as a cancer preventive agent the major problem is its low bioavailability. To achieve effective cancer prevention with curcumin, we studied the enhancing effects of EC from green tea, with curcumin. Our current results for the first time demonstrated that EC significantly enhances the cancer preventive activity of curcumin.