Figure 4

PER 2 expression induces apoptosis in MCF-7 breast cancer cells. (A) MCF-7 cells were transiently transfected with empty vector, vector expressing PER 2, or both vectors expressing PER 2 or CRY 2. After 72 hours, total cell extracts were prepared and subjected to Western blot analysis using an antibody directed against the 85 kDa cleaved fragment of PARP [poly (ADP-ribose) polymerase] (representative of three independent studies). (B) Densitometric analysis of cleaved PARP protein (average value of three independent studies). a. PER 2 or PER 2 + CRY 2 vs vector control, p < 0.001, b PER 2 + CRY 2 vs PER 2, p < 0.01