CHI3L1 and neoplasm: However, as YKL-40 produced by the tumor cells is thought to act on mouse cells/tissues rather than on the (human) tumor cells themselves, [16], [17], [28] plus there is no difference in proliferation of LOX cells under influence of anti-YKL-40, it is not easy to explain how the different entities might cause either an in- or decrease in tumor volume.