Similarly, NSCLC patients with activating mutations in EGFR are now routinely treated with erlotinib or other EGFR tyrosine kinase inhibitors, and testing for these mutations has become standard-of-care.51 In the clinic, we found that persistence of HRG mRNA expressing cancer cells is prognostic of poor response to standard therapy. This evidence concerns the gene EGFR and non-small cell lung carcinoma.