CD4 and neoplasm: In marked contrast, challenge with 3LL tumor cells expressing survivin as a weak TAA may not results in effective priming of CD8+ T cells, survival, and clonal burst, and as such require CD4+ T cell help not only during priming with tumor, but also vaccination with SA-4-1BBL/SVN to expand SVN-primed CD8+ T cells and/or affect the quality of these cells to the levels that are required for the generation of protective CD8+ T cell recall responses.