IL6 and melanoma: In a majority of melanoma cell lines and clinical specimens, constitutive phosphorylation of STAT3 at the Tyr705 residue has been observed, and this post-translational modification occurs in response to a variety of cytokines such as IL-6 (interleukin-6) which can be secreted in an autocrine fashion by melanoma cells, and is mediated by JAK2 kinase.