CD4 and neoplasm: Although less significantly, CD4+ T cells are also involved in DTC dormancy (Romero et al., 2014a, b; Borst et al., 2018) as they induce tumor cell dormancy and cell cycle arrest through TNFR1 and IFN-γ signaling in pancreatic cancer (Muller-Hermelink et al., 2008).