MTOR and lung cancer: To determine whether T4 induced autophagy in A549 and A549/DDP lung cancer cells through the inhibition of the PI3K/AKT/mTOR signaling pathway, cells were treated with T4 after pretreatment with PI3K, AKT or mTOR inhibitors (wortmannin, perifosine or rapamycin, respectively); the cell viability, PI3K and AKT activities, and expression of proteins involved in the PI3K/AKT/mTOR signaling pathway were measured.