Deoxypodophyllotoxin (DPPT), a natural flavolignan, exhibits anti-inflammatory and anti-tumor activities. However, the molecular mechanism of DPPT underlying the modulation of cell cycle progression is currently unknown. In this study, we determined the effect of DPPT isolated from Anthriscus sylvestris roots on the expression of cell cycle-regulatory proteins. We observed that DPPT treatment induced the arrest of cell cycle at the G2/M phase in HeLa cervix carcinoma cells. Immunoblot experiments demonstrated that DPPT causes the phosphorylation of ERK MAPK and p21Waf1/Cip1 as well as up-regulation of PLK1 and cyclinB1. This is accompanied by the activation of Cdc25C and Cdk1. These data suggest that DPPT may have a potential effect in the cell cycle arrest at the G2/M phase through the activation of the Cdk1/cyclinB1 complex through Cdc25C.