SLC6A8 and neoplasm: Without i.p. injection of creatine, no B16-OVA tumor growth difference was observed between CrT-WT and CrT-KO mice, likely due to the lack of sufficient creatine supply in these experimental mice to read out the creatine uptake difference between CrT-WT and CrT-KO mice (Fig. S1, I and J).