Collectively, these data, as well as previously published results, reveal that the PTEN gene act as a tumor suppressor by inhibiting cell proliferation, promoting cell apoptosis, and inducing cell cycle arrest in human lung adenocarcinoma in vitro and that these effects were somewhat mediated through a negative regulation of the PI3K/AKT/hTERT pathway. Here, PTEN is linked to lung adenocarcinoma.