Given that EGFR mutations correlate with an enriched STAT3 activation signature in human NSCLC and more than 50% of NSCLC tumors display activated EGFR-STAT3 signaling [31,59], phosphorylated STAT3 expression may be used as a biomarker to identify tumors with aberrant upstream EGFR signaling and stratify patients who are likely to benefit from EGFR inhibitors. The gene discussed is STAT3; the disease is non-small cell lung carcinoma.