RRM1 and cancer: We found that the mRNA expression of RRM1, RRM2, and RRM2B genes were up-regulated in 57.9% (11 of 19), 78.9% (15 of 19), and 0% (0 of 9), respectively, of the Oncomine cancer studies covering the four subtypes of LUSC, LUAD, large cell lung carcinoma (LCLC), and small cell lung carcinoma (SCLC) (Figure 4A).