An overview of the expected isotopologue distributions is presented in A. Increased serine biosynthesis was observed, along with increased generation of 13C5-ribose phosphate and higher adenosine synthesis in PH-Fibs at 24h from incubation with U-13C-glucose in B. (*, **, *** T-test p <0.05, 0.01, 0.001, respectively; n = 3).