Galbanic Acid, a Cytotoxic Sesquiterpene from the Gum Resin of Ferula asafoetida, Blocks Protein Farnesyltransferase - Cha, Mi-Ran; Choi, Yeon Hee; Choi, Chun Whan; Kim, Young Sup; Kim, Young-Kyoon; Ryu, Shi Yong; Choi, Sang Un (Planta Medica, 2011)