STAT3 and breast cancer: Patients with breast cancer bone metastases showed higher levels of serum IL-11, tumor tissue IL-11 messenger RNA (mRNA), and IL-11 immunohistochemical staining in comparison with patients with primary breast cancer only, associated with a higher expression of p-p38, p-c-JUN, and p-STAT3, suggesting that IL-11 plays an important role in regulating bone metastasis in breast cancer, and that its level in serum may be used to assess the risk of bone metastasis from primary breast cancer [77].