The pivotal position of CD4 T helper (Th) cells in helping B cells to produce antibody and control induction and maintenance of CD8 T cells [86] has led some investigators to focus on their importance in responses to DNA vaccination. By selecting genes encoding microbial proteins fused to the tumor antigen sequence, it was possible to activate Th cells and to dramatically amplify immunity against tumor cells [87] . As discussed in the following section, DNA vaccines offer the opportunity to activate Th cells and transform weak and ineffective immunity to a powerful antitumor attack [88] .