Figure 5. Taxol biosynthetic pathway. HMGS: 3-hydroxy-3-methylglutaryl-CoA synthase; HMGR: 3-hydroxy-3-methylglutaryl CoA reductases; MDD: MVA 5-diphosphate decarboxylase; DXS: 1-deoxyxylulose-5-phosphate; IDS: diphosphate synthase; IDI: isopentenyl-diphosphate isomerase; GPP synthase: geranyldiphosphate synthase; FPP synthase: farnesyl diphosphate synthase; GGPP synthase: geranylgeranyl pyrophosphate synthase; TS: taxadiene synthase; H-5α: cytochrome P450 taxadiene 5α-hydroxylase; TAT: taxa-4(20),11(12)-dien-5α-ol-O-acetyltransferase; H-10β: CYP450 taxane 10β-hydroxylase; T-13á: Taxane 13á-hydroxylase Multiple arrows indicate several steps.