RRM2 and glioma: For example, Ribonucleotide Reductase Regulatory Subunit M2 (RRM2) was a catalytic subunit of ribonucleotide reductase and functioned as a critical enzyme in the process of DNA replication and repair (Chabes and Thelander, 2000; Torrents et al., 2002; Nordlund and Reichard, 2006), and RRM2 has been proved negatively correlated with prognosis of glioma (Sun et al., 2019).