 YKL-40 also named chitinase 3 like-1 protein, CHI3L1, is a member of the mammalian chitinase like proteins and is a highly conserved glycoprotein. YKL-40 is produced by cancer cells and macrophages and promotes cancer progression by activating inflammation and inhibiting tumor angiogenesis. Thus, YKL-40 could be a new therapeutic target for patients with cancer. 