Aciculatin Induces Apoptosis via p53 Pathway Figure 5. p53 is required for aciculatin to trigger cell cycle arrest and apoptosis. A, p53-KO HCT116 cells were incubated with aciculatin (5– 10 mM) for 48 h. Cell viability was then determined by MTT assay. The results were compared with wild-type HCT116 cells. Mean 6 SE from 3 independent experiments. *P,0.05 and **P,0.01. B, p53-KO HCT116 cells were starved overnight and then incubated with vehicle (0.1% DMSO) or PLOS ONE | www.plosone.org 7 August 2012 | Volume 7 | Issue 8 | e42192