PIP and synovial sarcoma: Several proteins, such as lysozyme-C, lipocalin-1 (LCN-1), lysozyme proline-rich protein 3 (LPRR3), lysozyme proline-rich protein 4 (LPRR4), prolactin-inducible protein (PIP), and nasopharyngeal carcinoma-associated PRP4 and α-1antitrypsin, were decreased in tears of DED, SS, and MGD ocular patients [59, 61, 63, 168].