Olfactomedin-4 (OLFM4), previously called GC-1 (G-CSF stimulated clone-1) is an secreted glycoprotein that is a member of the Olfactomedin/Noelin family of protein . It is expressed in epithelial cells of the prostate, small intestine, colon, bone marrow, and in several cancers , and is up-regulated in epithelial cells during inflammation . Mature OLFM4 is a 490 amino acid (aa) protein that is secreted mainly in a polymeric form which is held together by disulfide bonds and carbohydrate interactions . Mature human OLFM4 shares 71% aa sequence identity with mature mouse and rat OLFM4. Olfactomedin-4 (OLFM4) interacts with cell surface lectins and cadherins, which helps cell adhesion and cell spreading of NIH3T3 and 293T/17 cells . OLFM4 plays a critical role in regulating progression of prostate cancer and is also novel biomarker for triple-negative breast cancer .