Methods and compositions are provided for assessing (e.g., diagnosing), treating, and preventing diseases, especially cancer, and particular lung cancer, using lung cancer markers (LCM). Individual LCM and panels comprising multiple LCM are provided for these and other uses. Methods and compositions are also provided for determining or predicting the effectiveness of a treatment or for selecting a treatment using LCM. Methods and compositions are further provided for modulating cell function using LCM. Also provided are compositions that modulate LCM (e.g., antagonists or agonists), such as antibodies, proteins, small molecule compounds, and nucleic acid agents (e.g., RNAi and antisense agents), as well as pharmaceutical compositions thereof. Further provided are methods of screening for agents that modulate LCM, and agents identified by these screening methods.