Two Cytotoxic Sesquiterpene Lactones from the Leaves of Xanthium strumarium and their in vitro Inhibitory Activity on Farnesyltransferase - Kim, Young Sup; Kim, Jeoung Seob; Park, Sung-Hee; Choi, Sang-Un; Lee, Chong Ock; Kim, Seong-Kie; Kim, Young-Kyoon; Kim, Sung Hoon; Ryu, Shi Yong (Planta Medica, 2003)