IL9 and neoplasm: The functional significance of this upregulation is unclear, as in the tumor cells the Foxp3 transcription factor remains restricted to the cytoplasm, contrary to nuclear localization in Tregs, but it may result in a lower immunogenicity of the tumor, as siRNA-mediated inhibition of Foxp3 expression in tumor cells may shift their cytokine expression pattern toward IL-6 and IL-9 secretion (72).