However, a previous study suggested the distinct roles of RRM2B in tumor progression: on one hand, its amplification was related to worse outcomes in breast cancers (Chae et al., 2016; Iqbal et al., 2021); on the other hand, in vitro analysis found its overexpression could inhibit the proliferation of lung cancer cells by the regulation work of FOXO3 (Cho et al., 2014). The gene discussed is FOXO3; the disease is breast cancer.