We found that DARPP-32, kinase-activated EGFR, total EGFR, kinase-activated ERBB3, and total ERBB3 proteins are upregulated in first-generation EGFR TKI-resistant NSCLC patient-derived specimens relative to individual patient-matched (i.e., paired) baseline samples biopsied prior to frontline gefitinib or erlotinib treatment (Fig. 9a, b). Here, EGFR is linked to non-small cell lung carcinoma.