Finally, in endometrial cancer cells, metformin presented antiproliferative effects by reducing IGF-1 secretion and IGF-1R expression, ultimately leading to the inhibition of downstream PI3K/AKT signaling [123], whereas considering breast tumors, in triple-negative cancer cell lines, a synergistic effect of metformin combined with an insulin/IGF-1 inhibitor in suppressing cell growth and proliferation was documented [124,125]. The gene discussed is IGF1; the disease is endometrial cancer.