LGR5 and neoplasm: Epidermal growth factor (EGF) was the most highly upregulated cytokine in tumor epithelial cells and Lgr5+ tumor epithelial cells compared with their corresponding controls (Figure 3, H and I), implying that tumor stem cell–derived EGF may be a key factor in STAT3 activation and subsequent transcriptional activation of OX40 in ECs.