The involvement of β-catenin in the C-peptide-enhanced MMP9/TIMP1 ratio and migration is consistent with the fact that β-catenin directly regulates the MMP9 promoter during endometriosis, which shows high potential for migration, and β-catenin and MMP9 increase in the impaired decidualization of isolated human ESCs from patients with endometriosis (Zhang et al., 2016). Here, TIMP1 is linked to endometriosis.