May play a role as marker for the diagnosis of metastatic breast cancer. Expressed in mammary, salivary glands and prostate. Also detected in lung. Mainly expressed in cancer cell lines of breast origin. Highly expressed in lymph node-positive compared with node-negative tumors. Detected in all lymph node containing metastatic cells. O-glycosylated. The number of repeats varies from 3 to 2 in one variant form which is equally present in breast cancer tumors.