ENTPD1 and colorectal cancer: CD39 activity has not yet been implicated in Treg immunosuppressive function in colorectal cancer, as it has in breast cancer where the addition of both an A2R-antagonist and an anti-CD39 antibody inhibited the suppressive effect of Treg on IFN-γ production by Th1 and CD8+ T cells in vitro [39].