Conversely, Prdx1-deficient mice tend to develop, amongst other malignancies, mammary carcinomas,37 and, similarly, the previous publication from our group has reported PRDX1 as a favourable prognosis biomarker in ER-positive breast cancer,9 which would implicate the role for PRDX1 as a tumour suppressor in mammary malignancies. The gene discussed is PRDX1; the disease is neoplasm.