To further investigate the mechanisms by which Net inhibits pancreatic ductal adenocarcinoma cell PL45 proliferation, several cell cycle associated genes (p21, p27, CDK2, CDK4, Cyclin D1, Cyclin E,c-Jun, and etc.)were evaluated at mRNA and protein levels 48 hours after Ad5/F35-Net infection. The gene discussed is CDK4; the disease is infection.