INHBA was up-regulated in melanoma-treated monocytes, and the exposure of activin A to human PBMC-derived monocytes and melanoma-treated monocytes, rather than wide type monocytes, could directly promote the transcription of protumoral cytokines such as CCL20, TNF and VEGFA, as well as immunosuppressive cytokines such as IDO-1 and PTGS2. Conditioned media of melanoma-treated monocytes could inhibit T cell proliferation and advance the invasion of melanoma cells. The gene discussed is IDO1; the disease is melanoma.