PLA signals corresponding to EGFR homodimers were higher in NSCLC cell lines and tissue specimens positive for activating EGFR mutations than in those wild type (WT) for EGFR. Stimulation with EGF in NSCLC cells WT for EGFR or forced overexpression of EGFR in Ba/F3 cells resulted in marked EGFR homodimerization. This evidence concerns the gene EGF and non-small cell lung carcinoma.