NR4A1 and neoplasm: This is the first report to describe the potential prognostic significance of MSK1 expression in breast cancer patients; although not an independent marker of outcome, we believe such findings and significant associations with well-established negative prognostic factors (low expression associating with younger age, higher tumour grade, higher Nottingham Prognostic Index, negative hormone receptor status, shorter time to distant metastasis, and recurrence, and triple-negative/basal-like status) warrant further examination and validation in independent patient cohorts.