CCNB1 and neuroblastoma: To compare the ability of 4h and 4k to act as antimitotic agents in neuroblastoma cells, we assessed the levels of phosphorylated serine-10 on histone 3 (p-S10-H3) or CYCLIN B1 following 24 h incubation with 4h, 4k, or a matched dimethyl sulfoxide (DMSO) control.