Consistent with these findings, we confirmed the positive correlation between RFC4 expression and the levels of NICD1 and HES1 in 219 NSCLC specimens collected in this study (Fig. 4h), suggesting a clinical relevance of the positive feedback loop consisting of activated Notch and high RFC4 levels during NSCLC development and progression. Here, HES1 is linked to non-small cell lung carcinoma.