CHEK1 and neuroblastoma: Some key elements have been shown to participate in the MDR process in NB, and include the increased expression of oncogenes such as MYCN, TrkB/BDNF signaling, or alterations in the DNA damage response (DDR) elements such as p53 [9–12], CHEK1 [13] or PLK1 [14, 15], among others.