a–c,Normalized labelling of serum glucose, lactate, and glutamine and of tumour TCA intermediates by infused 13C-glucose, 13C-lactate, and 13C-glutamine in three GEMM tumours in fasted mice. a, KrasLSL-G12D/+ Trp53−/− (KP) lung cancer (n = 3 for glucose and lactate and n = 4 for glutamine infusion). b, KrasG12D/+Stk11−/− lung cancer (n = 3). Stk11 is also known as Lkb1 and the mouse model is called KL lung cancer. c, KrasLSL-G12D/+Trp53−/−Ptf1aCRE/+ (KPf/fC) pancreas cancer (n = 3 for glucose and n = 4 for lactate and glutamine). Data are mean ± s.d. d, Direct circulating nutrient contributions to tumour TCA cycle, data are mean ± s.e.m. e, Schematic representation, glucose feeds the TCA cycle via circulating lactate.