Several microRNAs (miRNAs), such as miR-125a, miR-125b, miR-205, and miR-450b-3p, suppress HER3 expression by directly targeting the 3′ UTR of HER3 mRNA, inhibiting breast cancer (BC) cell proliferation and showing potential for treating mBC [119–121]. Here, ERBB3 is linked to breast cancer.