ALK and lung adenocarcinoma: Molecular characterization of lung adenocarcinoma have led to the correlation of activating mutations in the Epidermal Growth Factor Receptor (EGFR) with sensitivity to the EGFR tyrosine kinase inhibitors (TKI) gefitinib and erlotinib and also the identification of rearrangements of the ALK gene in distinct subsets of NSCLCs that are highly sensitive to the ALK inhibitor Crizotinib (Figure 1).