ENTPD1 and lung adenocarcinoma: Of note, cytokine-induced killer cells, a heterogeneous T cell population obtained by in vitro differentiation of peripheral blood mononuclear cells, as well as lung adenocarcinoma cell lines show no significant differences in CD39 expression regardless of being cultured either under 21% or 1% O2 (Horenstein et al., 2018; Giatromanolaki et al., 2020).