In line with that, mice bearing colorectal xenograft tumours fed with a diet lacking serine and glycine displayed a reduction in tumour volume and a prolonged survival.50 Moreover, several in vivo mouse experiments with PHGDH inhibitors alone or as a combined approach have shown positive antitumour effects in different tumour entities, such as breast cancer, renal cell carcinoma and hepatocellular carcinoma.51–53 Our data indicate that a combination of a serine/glycine-free diet with PHGDH inhibition could be an even more effective approach. The gene discussed is PHGDH; the disease is breast carcinoma.