ANXA5 and neuroblastoma: To investigate whether this was the mechanism of cell death in neuroblastoma cells susceptible to   sub-micromolar concentrations of CX-5461, we first used flow cytometry to quantify cells staining positive for annexin V and propidium iodide (PI), canonical markers of apoptosis and cell death respectively, following CX-5461 treatment at 0.1, 0.2 and 0.5 μM over 48 h.