CD4 and neoplasm: CD4-cre x IKKβfl/fl mice and control littermates were injected with MC57-SIY tumor cells, and on day 7 post-inoculation, a 1:1 ratio of CFSE-labeled T cell-depleted splenocytes loaded with SIY tumor antigen (exposed to low CFSE concentration) versus left unloaded (exposed to high CFSE concentration) was transferred intravenously into each mouse.