Furthermore, our findings suggest that GATA3 mutations may drive resistance to hormonal therapy by upregulating the PI3K/Akt/mTOR pathway, suggesting that inhibition of MDM2 may help overcome the resistance to PI3K/Akt/mTOR inhibition and/or to endocrine therapy in GATA3-deficient breast cancer. The gene discussed is GATA3; the disease is breast cancer.