In light of the above, it is reasonable for us to presume that the mechanism by which PTEN inhibits cell proliferation, promotes cell apoptosis, and induces cell cycle arrest in lung adenocarcinoma A549 cells may be related to the downregulation of hTERT expression and that the PI3K/AKT pathway might be implicated in this process. Here, PTEN is linked to lung adenocarcinoma.