Figure 3.

Dose response and kinetics of TS inhibition of apoptosis in PC12 cells. (A) Dose response. PC12 cells were grown in triplicate in serum-free RPMI in the presence of the indicated concentrations of TS, NGF, and VCNA for 17 h. Apoptosis was measured by counting cells with nuclear fragmentation after DAPI staining. Protection against apoptosis was measured by the formula described in MATERIALS AND METHODS. Data are representative of an experiment repeated three times with similar results. The molar concentration was based on a molecular mass of 200 kDa for TS, 26 kDa for NGF, and 90 kDa for VCNA. (B) Kinetics. PC12 cells in serum-free RPMI medium were grown in the absence (RPMI) and in the presence of 4.0 nM NGF and 0.5 nM TS for the times indicated. Cell viability was measured by determining the number of cells without nuclear fragmentation relative to those with nuclear fragmentation (DAPI staining) in a sample of 300–400 cells. The average of two experiments is shown, each point in triplicate.