Purvalanol A induction of apoptosis in MT-2. A) Purvalanol A induced caspase-3 and PARP cleavage in MT-2 and C8166 cells. MT-2, C8166, and CEM were treated with Purvalanol A at various 0.1, 0.5, 1, and 5 μM for 48 hr. After 48 hr of treatment, total cell extracts were collected and subjected to Western blot analysis of caspase-3 and PARP. Westeron blot of β-actin was used as an internal control. B) Twenty five microgram of each Purvalanol A treated (5 μM for 48 hr) extracts from both MT-2 and C8166 cells were also used for western blot against cyclin A, E and actin.