SMAD5 and breast cancer: Furthermore, we found that BC cells promoted SMAD5 expression in γδT1 cells via transfer of exosomal long non-coding RNA (lncRNA) SNHG16, which functioned as a ceRNA by sponging miR-16–5p and therefore potentiated the TGF-β1/SMAD5 pathway to upregulate CD73 levels.