STAT3 and leukemia: Many tumors such as breast carcinoma, lung cancer, esophagus cancer, and leukemia harbor aberrant STAT3 activity, which drives multiple pro-oncogenic functions [7,8,9].Tissue microarray showed that the expression of p-STAT3 in breast carcinoma is far above that of normal tissue and contributes to the high levels of downstream effector molecules, including apoptosis inhibitors (Survivin, Mcl-1, Bcl-XL, HSP27), cell-cycle regulators (c-Fos, MEK5, c-Myc), and inducers of tumor angiogenesis (VEGF, COX-2, MMP-2, MMP-10, MMP-1) [10].