RRM2 and mucoepidermoid carcinoma: We next validated enhanced expression of the top 10 genes (Mcm6, Prc1, Rrm2, Haus8, Pole2, Ccne2, Lig1, Dhfr, Mcm7, and Pcna) in MEC tumors, which were shared by both the RB1/RBL1 loss–induced and CDK4/6-RB integrated signatures by qPCR (Supplemental Table 3 and Supplemental Figure 10).