NR4A1 and neoplasm: The main clinical study reported that cytokeratin or mucin positive BM cells are associated with tumour size, grade, negative hormone receptors and lymph node metastases.1 Using a more stringent detection technique, we did not reproduce any of these results,8 although they have been confirmed by others.43 This might suggest that micrometastatic dissemination occurs in highly proliferative tumours, when a critical tumour size has been reached.