The pro-apoptotic role of ERK8 and NF-κB played in As2O3 cytotoxicity has been supported by the fact that short-hairpin RNA-specific knockdown of ERK8 or inhibition of NF-κB activity by NF-κB inhibitor in high ERK8-expressing human lung cancer H1299 cells blunted the As2O3-induced NF-κB activation and cytotoxicity towards these cells, indicating that both ERK8 and NF-κB are critical players in mediating the effects of As2O3. Here, MAPK15 is linked to lung cancer.