EIF2S1 and breast cancer: Paclitaxel and Adriamycin are the main drugs used in breast cancer neoadjuvant chemotherapy.24, 25 To examine the effect of these drugs on ISR induction, we treated breast cancer cell lines MDA‐MB‐231 and BT‐549 with these drugs and detected the phosphorylation of Ser51 residue on EIF2S1 and its downstream ATF4 expression.1 Western blotting showed that these two hallmarks of ISR could be robustly induced following paclitaxel treatment within only 1 hour (Figure 1A).