SMAD3 and cancer: Previously we found that the combination of two compounds isolated from herbal medicine, Asiatic acid (AA), a triterpene from Centella asiatica that functions as a Smad7 enhancer, and Naringenin (NG), a type of flavonoid mainly present in fruits as a Smad3 inhibitor, exert potent anti-cancer effects by rebalancing Smad3/Smad7 signaling and subsequently suppresses cancer progression by rejuvenating natural killer (NK) cell-mediated immune surveillance.25