On the other hand, tumour-associated stromal cells can also produce tumour suppressor factors, such as nucleoside diphosphate kinase A (NME1)6, Kangai 1 (KAI1/CD82)7, 8 and IL-25 (ref. 9), in the tumour microenvironment, and this can restrict the development or metastasis of breast cancers. The gene discussed is IL25; the disease is breast cancer.