MDM2 and hepatocellular carcinoma: The overexpression of TTLL4 led to the upregulation of PI3K, AKT, and MDM2, whereas the downregulation of TTLL4 resulted in decreased expression of these proteins, suggesting that TTLL4 may promote the proliferation and survival of HCC cells through the PI3K/AKT/MDM2 pathway [Fig. 6(e)].