CHI3L1 and neoplasm: Immunohistochemical analysis also showed that expression of Chi3L1 was lower in the tumor section of Chi3L1 shRNA mice, whereas the expression of p53 was markedly higher and its target proteins such as p21, BAX, and cleaved cas-3 consequently were increased in the section of Chi3L1 shRNA mice compared to those of control shRNA mice (Fig. 2d).