IGF1 and lung cancer: Since the klotho can inhibit the IGF-1/R signaling pathway in our previous study, and autophosphorylation of IGF-1R induces the activation of Akt by phosphorylation, we hypothesized that klotho could alleviate the resistance of lung cancer cells (A549DDP and H460DDP cells) to chemotherapeutics in which Akt plays an important role.