Prolactin-induced protein (PIP / GCDFP-15) is a secreted protein produced by benign and malignant salivary glands, sweat glands, seminal vesicles, apocrine cells and apocrine breast cancers, and extramammary Paget’s disease. In cancer, it is expressed in hyperplastic breast and breast carcinomas, including metastatic breast cancer. PIP is overexpressed in many of these carcinomas, where increased expression has been found to increase the cell adhesive and proliferative properties of malignant cells. This target typically stains secretions and may appear cytoplasmic, membranous, and/or extracellular. References: Biochemical and Biophysical Research Communications. 2015 Dec; 468.4; 850-856, PMID: 26585492; Advances in Experimental Medicine and Biology. 2015. 846; 189-200, PMID: 25472539;