The pentose phosphate pathway (PPP), also known as the hexose monophosphate shunt (HMP) or phosphogluconate pathway, is an alternative glucose metabolism pathway to glycolysis. It is more complex than glycolysis and takes place in the cytosol. The PPP is important for generating NADPH for biosynthesis of fatty acids, steriods, and maintaining glutathione levels, as well as producing pentoses used in nucleic acid synthesis. The pathway contains oxidative and non-oxidative phases, with glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase being the regulatory enzymes controlled by NADPH and pentose levels.