Cells with minimal expression of the JAK/STAT pathway related proteins STAT5a and the prolactin receptor: evidence of an alternate prolactin receptor isoform in breast disease.

Usually, wherever breast STAT5a is present, PRLR is reduced; without STAT5a PRLR becomes abundant. Five breast lesions essentially lacking both were tested immunohistochemically for PRLR isoforms. The intermediate isoform was essentially only detected in these lesions. In some breast lesions PRLR isoforms may be involved in JAK/STAT pathway disturbances.