The addition of exogenous IL-2 or a co-stimulatory antibody against CD28 did not noticeably improve the ex vivo response to melanoma cell stimulation in preliminary studies, but the proportion of T cells activated might, however, be enhanced through the use of these additional signals when using other antigen sources, or by using other growth factors e.g. GM-CSF [27], [28]. This evidence concerns the gene CSF2 and melanoma.