Figure 4

4HPR induced apoptosis in WT cell cultures. (A) 4HPR induced rounding and detachment of cells suggestive of cell death in cultures derived from tumors ws539 and ws568, while only few or no detached cell were found after 4d of treatment in cultures ws591 and ws592. (B) Increasing amounts of PARP cleavage as shown by Western blot analysis indicated apoptosis induction by 4HPR in WT cultures ws539 and ws568. ATRA and 9cis RA are less effective. For ws591 and ws592 no increase in apoptosis could be detected. β-actin was used as a loading control.