To control that any effects we might observe were specific to loss of Numb expression and not merely associated with an aggressive BC phenotype per se, we also selected four Numb‐proficient (Numb+) tumors (TA‐TD) with clinical–pathological parameters similar to those of the Numb− BCs (Fig 1A and B, and Appendix Fig S1A). Here, NUMB is linked to breast cancer.