We found that no matter the ROS–NRF2–HO-1 inhibition or NF-кB inhibition, it significantly attenuated DPP-4i-driven GM-CSF expression in BC cells (Figures 8F–I), suggesting an essential role of ROS–NRF2–HO-1–NF-кB axis in DPP-4i-driven GM-CSF production in BC cells. This evidence concerns the gene HMOX1 and breast cancer.