SIRT1 and columnar cell hyperplasia of the breast: In accordance with previous research indicating that SIRT1 plays a role in angiogenesis by modulating Notch1 signaling (Zhu et al., 2021), the current findings demonstrated that SIRT1 expression was reduced while DLL4 and nuclear NICD expression was elevated in rats with CCH in comparison to the sham rats (SIRT1, P < 0.01; DLL4, P < 0.001; NICD, P < 0.01, model group vs. sham group) (Figures 6A-D).