APEX1 and neoplasm: In order to test whether the secretion of APE1 through exosomes is a common feature of different mammalian cell lines, we performed EXE analysis in lymphocyte mouse isogenic cell lines, i.e., the non-tumor CH12F3Δ/+/+ and CH12F3Δ/Δ/Δ, expressing or not APE1 through genetic deletion, respectively (42).