Periodontal ligament cells (PDLCs) were incubated with H2O2 and the levels of XIAP protein, protein kinase B (AKT), phosphorylated forms of ART (pAKT), c-Jun N-terminal kinase (JNK), and glycogen synthase kinase-3 beta (GSK3 beta) were determined by western immunoblotting or immunocytochemistry. After overexpression and knockdown of XIAP, the ART, pAKT, JNK and GSK3 beta levels were determined in PDLCs exposed to H2O2. We demonstrated that 72 h of 250 mu M H2O2 exposure resulted in an increase in apoptosis. Meanwhile, XIAP levels were decreased with 72 h of 250 mu M H2O2 exposure, while there were also a decrease of JNK2, ART, pAKT, and GSK3 beta levels. Such reductions induced by 72 h of 250 mu M H2O2 treatment were partially recovered in PDLCs overexpressing XIAP. Interestingly, these reductions (except for pAKT) were mimicked by RNA interference of XIAP. These results suggest that, after 72 h of 250 mu M H2O2 exposure, Akt, JNK, and GSK3 beta intracellular kinase signaling pathways converge to regulate PDLC survival involving XIAP. (C) 2014 Elsevier Inc. All rights reserved.