IRF6 and squamous cell carcinoma: Thus, Botti et al. reported that IRF6 exhibits a tumor-suppressive function in squamous cell carcinomas [22]; Restivo et al. reported that IRF6 exerts tumor-suppressive functions in keratinocytes through mediation of Notch pro-differentiation [23]; Bailey et al. reported that IRF6 expression is decreased in invasive breast cancer cell lines and breast tumors [20] and that IRF6 facilitates mammary epithelial cell entry into the G0 phase of the cell cycle in collaboration with maspin [24].