The CHK1 inhibitor caused cell cycle arrest but did not enhance etoposide, doxorubicin, or cisplatin-induced apoptosis, suggesting that abrogation of the G2 cell cycle checkpoint may play an important role in the enhancement of etoposide, doxorubicin, or cisplatin-induced apoptosis by panobinostat in the high-risk neuroblastoma cells. Here, CHEK1 is linked to neuroblastoma.