FAS and neoplasm: Specifically, cytotoxic CD8 T cells kill tumor cells via degranulation of secretory granules or activation of the Fas/FasL molecular pathway, whereas CD4 T cells provide help for CD8 T cell stimulation, and produce pro-inflammatory cytokines (e.g. TNF-α, IFN-γ, etc.)and chemokines that attract further effector T cells into the tumor (Figures 1 and 2A).