CD80 and melanoma: Invasion of CD11c+ antigen presenting cells by uracil auxotrophs also increased CD80 and CD86 expression in melanoma and pancreatic cancer tumor microenvironments [15,19], and uracil auxotroph invasion of dendritic cells in naive mice increased the expression of CD80 and CD86 as well as MHCI that is required to initiate antigen presentation that drives the development of protective T cell populations [4].