This is expected as glutamine transporters are not only necessary for cancer cells, but they are also important for optimal lymphocyte proliferation and differentiation.40–43 In addition, macrophages may require glutamine as it is the main precursor for arginine.44 The latter can be catalysed by Arginase 1 to support cell proliferation and tissue remodelling.45 The gene discussed is ARG1; the disease is cancer.