In mature erythrocytes, the pentose phosphate pathway is impoant as a source of:
NADPH is used by glutathione reductase to maintain glutathione in the reduced form. Pentose phosphates are not needed in the red blood cell. The pentose phosphate pathway is not a source of NADH & ATP is not generated from NADPH.
Pentose phosphates
NADH to maintain heme iron in the ferrous form
For generation of energy in the form of ATP
NADPH to maintain glutathione in the reduced form