Recent studies have implicated YKL-40 in several biological processes such as inflammation, angiogenesis, apoptosis, cell proliferation, differentiation, and regulation of extracellular tissue remodeling [5], [7]–[21], all processes important for the progression of cancer cell growth, tumor angiogenesis, and metastatic potential [36]–[38]. The gene discussed is CHI3L1; the disease is cancer.