Effect of glucosamine on cell growth, cell cycle arrest, and apoptosis in NSCLC cells. (A) MTT growth assay of A549, H1299, and H460 cells. *P < 0.05 compared with glucosamine 0 mM. (B) NSCLC cells were treated with glucosamine for 2 days and then stained with PI for cell-cycle analysis. (C) Apoptosis/necrosis was determined by Annexin V-FITC and PI staining. (D) The protein levels of CDK2, CDK4, PARP, and cleaved PARP.