RRM2 and colorectal carcinoma: By analyzing all CRC data from Oncomine, we showed that the mRNA level of RRM2 was mostly increased among three RR subunits, ranking in the top 10% of the upregulated differentially expressed genes (DEGs) in 34.3% of the studies (12 of 35), in comparison with 11.1% (4 of 36) and 18.2% (6 of 33) for RRM1 and RRM2B, respectively.