During storage, RBCs undergo changes known as storage lesions that include shape change and the loss of DPG. Several hours of warm rejuvenation with PIPA solution will increase RBC DPG and partially restore morphology but with significant loss of membrane. The data from Dumbill et al suggest that the lower hemoglobin affinity is more important than the shape change with its longer path for individual oxygen molecules out of the RBC. Professional illustration by Patrick Lane, ScEYEnce Studios.