TRAIL secreted by the Mono Mac 6 cells after the stimulation with AP-PG is able to induce apoptosis to HeLa cells.

<p>(A) Mono Mac 6 cells (3 × 10⁵ cells/ml) were stimulated with AP-PG at a concentration of 100 μg/ml. After 48 hrs, the supernatant of the cultured medium was collected, and HeLa cells (2.5 × 10⁴ cells in 24 well plate) were cultured in the supernatant with 100 ng/ml cycloheximide for 3 hrs. After the incubation period, the caspase-8 activity was measured using Caspase Glo Assay kit (Promega). 1 μg/ml neutralizing antibody for TRAIL was added to the supernatant for monitoring the dependence of TRAIL on the caspase-8 activation. HeLa cells incubated in the growth medium with 100 μg/ml AP-PG were used as a negative control, and HeLa cells stimulated with 20 ng/ml TRAIL were used as a positive control for the TRAIL neutralizing antibody. Error bars indicate standard deviations calculated by three independent experiments and the double asterisks (**) represent p<0.01.