APEX1 and melanoma: We have concluded that the interrelationship between BER and PTEN may be a valid therapeutic target in melanoma for the following reasons: a) PTEN-deficient cells are sensitive to APE1 repair domain inhibitors; b) PTEN-deficient cells are sensitive to methoxyamine, an indirect inhibitor of APE1; c) PTEN-deficient cells are sensitive to the PARP inhibitor NU1025; and d) upon APE1 inhibitor treatment, PTEN-deficient cells accumulate DNA DSBs, resulting in the induction of apoptosis.