The STAT3 signaling pathway is especially important for cell proliferation, anti-apoptosis, chemoresistance, metastasis and angioneisis, and cancer immune evasion through constitutive phosphorylation of STAT3 or in response to interleukin-6 (IL-6) provided by cells in the bone marrow microenvironment or by tumor cells (Zhong et al., 1994). Here, STAT3 is linked to cancer.