In urothelial carcinoma, the activation of EGFR can upregulate the expression of SOX9 via the ERK signaling pathway, thereby promoting tumor occurrence; the EGFR-ERK-SOX9 signaling cascade mechanism suggests that a similar regulatory pathway may also exist in EGFR-mutated NSCLC (44). The gene discussed is SOX9; the disease is urothelial carcinoma.