Past literary insights on A549 lung cancer cells discovered that isorhamnetin at a concentration of 20 μg/mL can induce apoptosis in A549 cells, upregulate the expression of apoptotic genes Bax, Caspase-3, and p53, and downregulate the expression of Bcl-2, cyclin D1, and PCNA proteins. This evidence concerns the gene PCNA and lung cancer.