As reported in the literature, the overexpression of FOXM1 in breast cancer can interact with Smad3/Smad4 to inhibit the binding of TRIM33 and Smad4, thus preventing its ubiquitination, thus weakening the inhibition of TRIM33 on transforming growth factor-β signal, thus promoting breast cancer metastasis [15]. Here, SMAD4 is linked to breast cancer.