Activation of the epidermal growth factor receptor (EGFR) family is ahallmark of many cancers.19 EGFR are found in keratinocytes and can be activated by epidermal growthfactor (EGF) or transforming growth factor α (TGF-α).20,21 Growth factor secretion from the tumor may drive keratinocyte growth via EGFRsignaling, resulting in ESK. The gene discussed is EGF; the disease is cancer.