DLL4 and lung cancer: Notch1 is detected in 50% of stage I to IV NSCLC cases, predominantly localized to the cell membrane and cytoplasm.128 Meta-analysis reveals that high Notch1 expression correlates positively with lymph node metastasis and higher tumor-node-metastasis (TNM) stage, indicative of poor OS in patients with NSCLC.129 Wang et al. identified significantly higher positive rates of Notch4 and DLL4 in NSCLC compared to normal lung tissues.130 However, contradictory findings emerge from another study, reporting downregulated DLL4 protein levels in NSCLC tissues and lung cancer cell lines.