FTI 277 is a prodrug form of FTI 276 that inhibits farnesyltransferase (FTase) (IC50 = 0.5 nM). Inhibits H-Ras and K-Ras processing in whole cells (IC50 values are 0.1 and 10uM respectively) and disrupts constitutive H-Ras-specific activation of MAPK. Causes significant antiproliferative effects in human malignant glioma cells and many other tumor cell lines.