STAT3 and cancer: The activation of signal transducer and activator of transcription 3 (STAT3) is usually transient in normal cells, but STAT3 has been reported to be present in a constitutively activated state and to promote tumorigenesis by enhancing cell proliferation, survival, and angiogenesis while suppressing the anticancer immune response in many different types of cancers, including colon cancer, melanoma and myeloma [15–17].