Effects of Ursolic Acid, Betulin and Sulfur-Containing Compounds on Mucin Release from Airway Goblet Cells - Lee, Choong Jae; Seok, Jeong Ho; Hur, Gang Min; Lee, Jae Heun; Park, Ji Sun; Seol, In Chan; Kim, Yun Hee (Planta Medica, 2004)