Similarly to PVRL4, integrin β4 expression is associated with poor prognosis and a basal-like expression profile (Diaz et al., 2005; Lu et al., 2008), and targeting integrin β4 with RNAi was shown to inhibit anchorage-independent growth, invasion, and xenograft growth in breast cancer cell lines (Lipscomb et al., 2003; Bon et al., 2006). Here, NECTIN4 is linked to breast cancer.