Pentose phosphate pathway: phases, reactions, & metabolic roles HMP also known as the Pentose phosphate pathway. Consists of two irreversible oxidative rxs followed by a series of reversible Glucose metabolism begins with its transport into cells via GLUT transporters, where it is phosphorylated to glucose 6 phosphate (Glucose 6 P). This molecule can enter various pathways, including the pentose phosphate pathway or hexosamine biosynthesis. biochemistry Why is the Pentose Phosphate Pathway so active in erythrocytes? Biology Stack Exchange