STAT3 and breast cancer: Single-cell RNA sequencing data reveal that IL-10 mRNA levels in Bregs within the Dex-treated breast cancer microenvironment increase by 3- to 5-fold.Second, at the metabolic level, Dex enhances STAT3 phosphorylation (p-STAT3), thereby boosting mitochondrial oxidative phosphorylation in Bregs, enabling them to maintain an immunosuppressive phenotype even in low-glucose microenvironments (30).