Induction of apoptosis in melanoma cell lines by UNBS1450. Apoptosis induction following UNBS1450 treatment was evaluated by means of double annexin V (AV) and propidium iodide (PI) staining analyzed by flow cytometry in VM-21 and SKMEL-28 cells. (A) Plots generated by flow cytometry for VM-21 cells left untreated (Aa) or treated for 15 hrs with 100 nM UNBS1450 (Ab). (B) Quantitative data for the percentage of cells presenting each staining combination are given for VM-21 cells treated for 15 hrs (Ba) and SKMEL-28 cells treated for 40 hrs (Bb) with 0, 10, 50 or 100 nM UNBS1450 (legend as detailed in [Aa]). (C) PARP cleavage analysis by means of Western blot in VM-21 (Ca) and SKMEL-28 (Cb) cells, respectively, treated either with 10 or 100 nM of UNBS1450 for up to 48 hrs. Apoptotic PARP fragments have a molecular weight of approximately 85 kD, whereas necrotic fragments are approximately 55 kD compared with the native protein, which is 116 kD. Tubulin was used as the loading control.