"overexpression of phospho-ALK and alternative receptor tyrosine kinases such as phospho-EGFR phospho-HER3 and phospho-IGFR-1R was observed in both resistant cell lines. Additionally NRG1 a ligand for HER3 is upregulated and responsible for resistance by activating the EGFR family pathways through the NRG1-HER3-EGFR axis."xsd:string