Transfection with siRNA targeting the immunoproteasome alters proteasome-mediated antigen processing by the dendritic cell, generating TAA-derived peptides that we hypothesize, based on preclinical results, will induce enhanced anti-melanoma immune responses. This phase I study, open to subjects with metastatic melanoma, will assess the safety of vaccination with melanoma tumor associated antigen-encoding RNA-transfected mature dendritic cells derived from monocytes that have been either untreated, transfected with control siRNA, or transfected with siRNA targeting the inducible immunoproteasome beta subunits LMP2, LMP7, and MECL1. A combination of RNAs encoding melanoma tumor associated antigens MART-1, tyrosinase, gp100, and MAGE-3 will be utilized for dendritic cell transfection. The vaccine will be administered by intradermal injection in the extremities. Clinical and laboratory toxicities will be characterized for each study arm. As a secondary objective, this phase I study will also assess the anti-melanoma immune responses, as well as clinical responses, induced by vaccination with this dendritic cell-based product.