The key role that MCTs play in regulating lactate homeostasis in tumours together with the upregulation of MCT1 and MCT4 expression observed in many cancers has led to much interest in targeting these proteins for cancer treatment.4,6–8 To date, several inhibitors of MCT1 have been reported that exert promising activity in experimental cancer models, including SR138009 and AZD3965,10 and progress is being made towards the development of MCT4-targeted agents (AstraZeneca). The gene discussed is SLC16A1; the disease is cancer.