In a PTEN-defective melanoma cell line engineered to express PTEN under a tetracycline-responsive promoter, PTEN negatively regulated the expression of the immunosuppressive cytokines interleukin (IL)-10, IL-6, and vascular endothelial growth factor (VEGF) by inhibiting signal transducer and activator of transcription (STAT)3. This evidence concerns the gene PTEN and melanoma.