RRM2 and rheumatoid arthritis: We found that the expression of 10 hub genes, including BUB1, RAD51AP1, DLGAP5, kinesin family member 11(KIF11), MAD2L1, RAD51, thymidylate synthase (TYMS), RRM2, cell division cycle 20(CDC20), and cluster of differentiation 2(CD2), were all upregulated in patients with RA in the dataset GSE77298, GSE55235 and GSE55247 datasets (Fig 1D).