IDO1 and cancer: The prevention of intra-tumoral immunosuppressive IDO+MDC infiltrate, due to IL-30 silencing in PC-SLCs, likely boosts the cytotoxic and tumoricidal activity of T lymphocytes, as suggested by the frequency of caspase-3+ apoptotic cancer cells close to CD3+T lymphocytes, which express cytotoxic molecules perforin, TRAIL or FasL.