the invention is a method of treating , inhibiting or controlling a ras - associated disease by inhibiting farnesyl - protein transferase enzyme , treating ras oncogene - dependent tumors , which include cancers of pancreas , breast , lung , colon , epidermis , prostate , bladder , thyroid , myelodysplastic tumors and myeloid leukemia ; controlling metastasis , suppressing angiogenesis , inducing apoptosis , and in treating ras - associated proliferative diseases other than cancer , such as restenosis , neuro - fibromatosis , endometriosis , and psoriasis , in a mammal in need thereof , which comprises administering to said mammal an effective amount of a compound of formula i : or a pharmaceutically acceptable salt thereof , wherein r 1 , r 2 , r 3 , r 4 , r 5 , q , a , and b are defined in the specification .