EBV Blocks NOXA Induction Figure 4. BL31 cells established using BHLOC KO become partially sensitive to ionomycin treatment. (A) EBV-negative BL31 and its EBV- positive converts established using recombinant B95.8 (WT), BHRF1 locus-knockout (BHLOC KO) and BHRF1 locus-revertant (BHLOC rev) EBVs were treated with 1 mg/ml ionomycin (IM) or DMSO (vehicle control). After 24 hours cell viability was determined using the CellTiter-Glo assay and expressed relative to vehicle-treated cells. The mean and standard deviation from three independent experiments are shown. (B) Protein extracts from cells harvested at 24-hour intervals were separated by SDS-PAGE and analysed by western immunoblotting using antibodies that detect full- length and cleaved PARP. Ionomycin-treated cells are compared to the same cells treated with vehicle control for 48 hours (U) and c-tubulin was used as a loading control. doi:10.1371/journal.pone.0028506.g004 PLoS ONE | www.plosone.org 7 December 2011 | Volume 6 | Issue 12 | e28506