CTLA4 and cancer: Inhibition of ENTPD2 by ARL67156 and POM-1 reduces tumor growth and improves the effectiveness of immune checkpoint inhibitors of programmed death-1 (PD-1) (clone RMP1-14) and cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) (clone 9D9), implying that ENTPD2 is a prospective cancer treatment target [111].