We found that the expression of DPP4/CD26 was significantly increased in BrdU-, GEM- and PALBO-induced senescent MCF-7 and MDA-MB-231 cells and in BrdU-treated breast cancer cell lines (CAMA-1, MDA-MB-468 and T47D), indicating that it could be a potential new marker of senescence in breast cancer. This evidence concerns the gene DPP4 and breast cancer.