HMG-CoA reductase is a rate-limiting enzyme in the mevalonate pathway. Statins inhibit the activity of HMG-CoA reductase and limit the production of isoprenoid intermediates and cholesterol. Farnesyl pyrophosphate (FPP) and geranylgeranyl pyrophosphate (GGPP) serve as lipid donors for protein prenylation. Farnesyl transferase inhibitors (FTIs) and geranylgeranyl transferase-1 inhibitors (GGTIs) block protein farnesylation and geranylgeranylation, respectively (see text for details). PP, pyrophosphate; FPPS, farnesyl PP synthase; GGPPS, geranylgeranyl PP synthase; SS, squalene synthase; FT, farnesyl transferase; GGT-1, geranylgeranyl transferase-1; GGT-2, geranylgeranyl transferase-2 (a.k.a., RabGGT).