YKL-40 also seems to promote tumor angiogenesis in colon and breast cancer [23], an effect that could point to a common pathway for several disease processes, where YKL-40 is expressed in monocytes, stimulates monocyte maturation and differentiation to macrophages, and stimulates macrophage activation and promotes angiogenesis. The gene discussed is CHI3L1; the disease is breast carcinoma.