FIGURE 5.

ATF4 knockdown suppresses ZER- or CCB-induced expression of CHOP, ATF3, and DR5. ATF4 was knocked down in HCT116-p53null cells, and these cells were treated with 40 mm ZER (a) or 50 mm CCB (b) for 24 h. Expression of ATF4, CHOP, ATF3, and DR5 was measured by Western blotting (left panel) and qRT-PCR (right panel), respectively. siCtrl, control siRNA. c, cell surface expression of DR5 of control or siATF4 cells was measured after ZER (left panel) or CCB (right panel) treatment as under “Experimental Procedures.” Shaded no line, vehicle with control IgG; thick line, vehicle with anti-DR5 antibody; thin line, ZER or CCB of control cells with anti-DR5 antibody; dashed line, ZER or CCB of siATF4 cells with anti-DR5 antibody. *, p < 0.05; **, p < 0.01.