CTLA4 and neoplasm: RT-qPCR and Western blot results showed that compared with the MDA-MB-231 group, CHI3L1, MAF and CTLA4 expressions were significantly upregulated in tumor tissues of BCSCs-231 group, and after exogenous administration of anti-CHI3L1, there was no significant change in CHI3L1 expression in BCSCs-231 + anti-CHI3L1 group compared with BCSCs-231 group, and MAF and CTLA4 expressions were significantly decreased (Fig. 6B, C).