The same experimental conditions were applied to a control group, except that the medium contained PBS in place of the toxins. The cell viability of the control group (in the absence of toxins) was

set as 100%. B16-F10 cell membrane ghosts were obtained from approximately 5 × 108 cells. B16-F10 cells were lysed and washed in Hypo-osmotic Buffer (NaH2PO4 5 mM, PMSF 2 mM and pH 8.0). The lysed cells were collected via centrifugation (12,000 × g, 10 min, 4 °C); this procedure was repeated four times. The B16-F10 cells ghosts were resuspended in 1 mL of cold extraction buffer (Tris–HCl 50 mM, NaCl 150 mM, Triton X-100 0.5%). After gentle homogenization for 10 min at 4 °C, the suspension was centrifuged at 20,000 × g for 20 min at 4 °C, and the supernatants were collected for subsequent PARP inhibitor use. The ghosts and extracts (50 μg of protein) were utilized as substrates for LiRecDT1 (10 μg) in a total final volume of 250 μL for 5, 15 or 30 min or selleckchem 1, 3, 6, 12 or 24 h, at 37 °C, followed by gentle mixing using a rotational shaker in a BOD incubator. The contents of the treated tubes were then added to a 250 μL reaction mixture adapted from the Amplex Red Sphingomyelinase Assay Kit (Molecular Probes) containing choline oxidase (4 U), alkaline phosphatase (80 U), horseradish peroxidase (20 U), and the Amplex Red reagent (100 μM), excluding

the sphingomyelin substrate. After incubation in a water bath for 30 min at 37 °C, fluorescence was measured in a Tecan Infinite® M200 spectrofluorometer Florfenicol (Tecan) with excitation at 540 nm and emission detection at 570 nm. B16-F10 cells (0.5 × 103) were incubated with LiRecDT1 for 5 h (10 μg/mL), and 100 μL of the cell suspension was applied to coverslips for adhesion. Unbound cells were removed by washing 10 times with PBS, and adherent cells were fixed with 4% paraformaldehyde in PBS for 30 min at 4 °C. The cells were then incubated with 0.1 M glycine for 3 min and washed with PBS; then, prior to incubation with antibodies, the non-specific

binding sites were blocked by incubating the coverslips in blocking buffer (PBS containing 1 mg/mL BSA, 0.1 M glycine) for 20 min. The samples were stained to detect phospholipase-D via indirect immunofluorescence using antibodies incubations at a 1:1000 dilution in PBS (anti-LiRecDT1) for 2 h. After washing with PBS, the slides were incubated for 1 h with the secondary antibody Alexa-Fluor-594 conjugated anti-rabbit IgG (1:500) in PBS. For the antigen competition assays, the immunofluorescence protocol was the same as described above, except that hyperimmune IgG against recombinant LiRecDT1 phospholipase-D was previously incubated with 100 μg/mL of LiRecDT1 diluted in PBS for 1 h at 37 °C. Then, the mixture was incubated with treated B16-F10 cells as described above. To analyze nuclear fluorescence, cells were incubated with DAPI (4′-6-Diamidino-2-phenylindole) (300 nM diluted in PBS) for 5 min.