In the current study, bevacizumab treatment led to reduced DLL4 expression and inhibited the NOTCH signalling pathway, as confirmed by the downregulation of the NOTCH target gene, HEYL. These findings support the hypothesis that bevacizumab exerts its antitumour effects through inhibition of VEGF, as well as the NOTCH signalling pathway, which may explain the disruption of tumour angiogenesis [33]. The gene discussed is HEYL; the disease is neoplasm.