HDAC1 and neuroblastoma: The increased anti-proliferative and pro-apoptotic effects observed in M344-treated NB cells (Figure 4 and Figure 6) may be mediated through enhanced suppression of HDAC1, a known mediator of cell cycle checkpoint progression and apoptosis, as M344 HDAC1 IC50 is roughly half of that required by vorinostat in HEK293 cells [9,29,37].