CDK4 and lung adenocarcinoma: Previous studies found that FEZF1-AS1 knockdown repressed the proliferation of gastric cancer and lung adenocarcinoma cells, inhibited cell cycle progression by causing G1/S arrest, and decreased the levels of cyclin-dependent kinase 2 (CDK2), cyclin-dependent kinase 4 (CDK4), cyclin-dependent kinase 6 (CDK6), and cyclin D1 [10, 11].