Moreover, the expression level of EGFR and CXCR4 in serum sEVs correlated well with the ones in the primary tumor tissues as assessed by IHC, suggesting that sEV-based assessments could be used as a noninvasive surrogate to the tissue-based examination by IHC and therefore had potential in clinical application. The gene discussed is CXCR4; the disease is neoplasm.