RRM2 and renal cell carcinoma: Ribonucleotide reductase subunit M2 (RRM2) is a ribonucleotide reductase (RNR) subunit that catalyzes the synthesis of deoxyribonucleotides.[12] RRM2 overexpression has been reported in many types of cancer and has been implicated in tumor progression.[13] Additionally, microRNA (miR)‐99a‐3p targeting RRM2 mRNA is often downregulated in sunitinib‐resistant RCC cells,[14] suggesting that RRM2 may be overexpressed in sunitinib‐resistant RCC cells.