ENTPD1 and neoplasm: CD39 expression can shape immunity in the long term, interfering with the formation T follicular helper cells66 and long lived memory T cells.67 Expression of CD39 on CD4+ T cells in aged individuals correlates with increased susceptibility to apoptosis which can be reversed by CD39 inhibition illustrating a role for CD39 in regulating T cell longevity.67 Increased susceptibility to apoptosis is also a feature of tumor infiltrating T cells and limits effective anti-tumor immunity47 and increasing CD39 expression may represent a novel means by which CAF favor T cell apoptosis in the TME.