MTHFD1L and familial pancreatic carcinoma: We then performed metabolic rescue experiments with 50 μM thymidine, 50 μM hypoxanthine or 1 mM sodium formate using RPMI-dFBS in SW620 WT cells and in cells deficient in mitochondrial 1C metabolism: SW620 MTHFD2−/− cells and MTHFD1L-defective PA-TU-8988T pancreatic cancer cells13 (Fig. 3h–o and Extended Data Fig. 3c–e).