Fig. 8. CHOP knockdown delays CPA- and FFA-mediated β-cell apoptosis. INS-1E cells were transfected with siRNA against CHOP mRNA (si, gray bars), negative (inactive) siRNA (N, black bars) or empty liposomes (C, white bars) and exposed to CPA (positive control), 0.5 mM palmitate or vehicle (control) for 6-24 hours. (A,B) One representative CHOP western blot after 24-hour exposure and optical densitometry of CHOP protein expression from four independent experiments are shown. Results are expressed as CHOP protein normalized to β-actin protein (used as a loading control) and are means ± s.e.m. (C,D) Percentage of cells undergoing apoptosis after exposure to CPA for 6-24 hours (C) or palmitate for 14-24 hours (D). Results are means ± s.e.m. of four to seven independent experiments. ^*P<0.05, ^**P<0.01, ^***P<0.001 vs control; #P<0.05 vs non-transfected cells.