We further analyzed the hippocampal expression of EGF and ErbB1 using ELISA and western blotting respectively (see details in the Supplementary Figure S1) and observed the up-regulation of EGF and ErbB1 expression during CCH, which is consistent with the previous research (Ashok et al., 2016). This evidence concerns the gene EGFR and columnar cell hyperplasia of the breast.