Although the precise function of YKL40 is not clear, it is presumed to play a pivotal role in the proliferation and differentiation of cancer cells, support cell survival by activating protein kinase B (AKT) and inhibit apoptosis (Chen et al. 2011), stimulate angiogenesis (Faibish et al. 2011, Francescone et al. 2011), influence extracellular tissue remodelling (Johansen 2006) and act as a growth factor for fibroblasts (Recklies et al. 2002). This evidence concerns the gene CHI3L1 and cancer.