Improved PTR and antioxidant metabolism in RBCs from Sphk1 KO mice. (A-C) Storage of mouse RBCs from WT C57BL/6 and Sphk1 KO mice (A) resulted in altered metabolism (heat map in panel B), including significantly lower levels of RBC S1P (C), as expected. (D) Specifically, Sphk1 KO stored RBCs were characterized by lower levels of glycolytic metabolites (hexose phosphate, fructose bisphosphate, glyceraldehyde-3-phosphate, and DPG) and higher levels of PPP metabolites (6-phosphogluconate, sedoheptulose phosphate). Sphk1 mice had higher PTR (P < .05) than WT good storer mice (median ± ranges) (E). In panel E, 1 data point for PTR in Sphk1 mice was set to 100%, as explained in “Materials and methods.”