A, Relative intracellular phosphocreatine and ATP levels in LvM3b cells expressing a control shRNA or shRNA targeting SLC6a8 (n=4). B, Liver metastasis by 5 × 105 LvM3b cells expressing two independent short hairpins targeting SLC6a8 (n=5). C, Liver metastasis by SW480 cells over-expressing CKB with and without SLC6a8 depletion (n>4). D, In vitro survival of LvM3b cells depleted of CKB, SLC6a8 with and without phosphocreatine supplementation in hypoxia (n=3). Error bars, s.e.m; all P values are based on one-sided Student’s t-tests, or where appropriate, Mann-Whitney test for non-Gaussian distribution. *p<0.05; **p<0.001; ***p<0.0001. See also Figure S5.