CD4 and neoplasm: Considering the scenario that during initiation only a low number of CSCs remain in the site of tumor origin in comparison to higher number of infiltrating T cells [40, 41], next in an attempt to mimic such condition, anti-CD3/anti-CD28-activated CD4+ T cells (for 72 h) were cultured in the CM of 72 h culture of purified MDA-MB-468 CSCs, at the CSC:T cell ratio of 1:5, as depicted by the schematic diagram (Fig. 2B).