CCNB1 and cancer: The gene expression levels of cyclin B1 (CCNB1), cyclin B2 (CCNB2), Aurora A (AURKA), Aurora B (AURKB), and PLK-1 (PLK1) were increased from stages 1 to 4; however, the genes for D-type cyclins were expressed in a stable manner across the cancer stages (Figure 3).