Abstract: The instant application provides methods and related compositions pertaining to the identification of resistance to anticancer treatment in a patient. In a particular embodiment, the invention provides biomarkers for the identification of resistance to anticancer treatment in a lung cancer patient, wherein a reduced expression of a MEDIATOR and/or SW1/SNF complex gene in the lung cancer cells of the patient indicates that the lung cancer cells in the patient may be resistant to treatment with a receptor tyrosine kinase inhibitor, such as gefitinib and/or erlotinib. In some embodiments, the invention relates to methods and related compositions for predicting resistance to anticancer treatment by detecting the expression levels of one or more TGF-beta pathway nucleic acids and/or proteins.