MAD2L1 and hepatocellular carcinoma: Pearson correlation revealed a prominent 4-gene cluster in which mitotic arrest deficient 2 like 1 (MAD2L1), cyclin A2 (CCNA2), and BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) were well characterized in HCC and the cell cycle (Fig. 2D).