PDE4D and hepatocellular carcinoma: Interestingly, when we explored with GEPIA the connections between PDE4D gene expression and overall survival in the above-mentioned samples, the Kaplan-Meier curve revealed that HCC patients with higher levels of PDE4D expression showed a worse prognosis than those with a lower level of PDE4D expression, but the difference was not statistically significant (Figure S1C).