G2 and S phase‐expressed 1 (GTSE1) is a cell cycle‐related protein encoded by the human gtse1 gene, which mainly regulates G1/S cell cycle transition.14 Recent years' research shows that GTSE1 is associated with cancer cell survival, metastatic behaviour and chemoresistance.15 It has been proved that GTSE1 was related to multiple drug resistance including cisplatin, 5‐fluorouracil and adriamycin.16, 17 As the role of GTSE1 in tumour getting more and more attention, GTSE1 study involved a variety of tumours including HCC, gastric cancer and breast cancer, except lung cancer.17, 18, 19. Here, GTSE1 is linked to breast cancer.