To determine whether increased T cell responses were responsible for DAC-induced tumor regression, C57BL/6 mice with established EL4 tumors treated with DAC were also treated with anti-CD8 or anti-CD4 antibodies or their relative control antibodies i.p. Anti-CD8 or anti-CD4 treatment resulted in complete depletion of CD8+ or CD4+ cells from spleens and tumors (Figure 3A, C). This evidence concerns the gene CD4 and neoplasm.