p13 increases cell death of tumor cell lines in response to glucose deprivation. Specific death of Jurkat (A) and HeLa (B) cells in response to glucose deprivation was calculated as described in “Analysis of ROS production in living cells.” In both cell types, p13 expression significantly enhanced cell death induced by glucose deprivation. Specific cell death triggered by p13 in response to glucose depletion was abrogated by treatment with NAC. (C-D) Comparison of the levels of cell death detected in the HTLV-1–infected cell line C91PL (C) and in p13-expressing Jurkat cells (D) in the presence (gray histogram) or absence (open histogram) of glucose. Dead cells measured in the gate areas R1 were 16.84% in the presence of glucose and 37.83% in the absence of glucose for C91PL cells, and 10.01% in the presence of glucose, and 17.10% in the absence of glucose for Jurkat-p13 cells. (E-F) Results of real-time RT-PCR to quantitate p13 (E) and tax/rex (F) mRNA copy number (normalized for GAPDH), in response to treatment with p13 siRNA. (G) The effects of p13 silencing on glucose deprivation–induced C91PL cell death. (H) The reversion of the effects of p13 siRNA upon cotransfection of a plasmid expressing p13-GFP. Indicated P values were calculated with the Mann-Whitney test.