Expression of Cyclin Dl, CDK4 and p21 in the different groups. Cells were treated with (A) 0, (B) 25, (C) 50 and (D) l00 µg/l dipsacus saponins. Levels of Cyclin Dl and CDK4 expression increased in groups treated with 50 and l00 µg/l dipsacus saponins. By contrast, levels of p21 expression decreased in the groups treated with 50 and l00 µg/l dipsacus saponins. CDK4, cyclin-dependent kinase 4.