Immunofluorescent analysis of CHI3L1 in paraformaldehyde fixed cells with polyclonal antibodies to CHI3L1 indicated that the protein was localized diffusely in cytoplasm of 293 cells stably expressing CHI3L1 (Fig. 3), corresponding to the localization of CHI3L1 protein in breast cancer cells (18). This evidence concerns the gene CHI3L1 and breast cancer.