Alternate patterns of reactivity can also stem from what was interpreted as positive immunostaining; in this report we have made a distinction between the often faint luminal expression of PRLR seen in normal breast tissue of the type previously reported (Gill et al. 2001) and the much stronger cytoplasmic immunostaining observed in most human breast carcinomas where STAT5a was not expressed. The gene discussed is PRLR; the disease is breast carcinoma.