Gadd45β does not block the “intrinsic” pathway for apoptosis. PI nuclear staining of HA-Gadd45β, Bcl-x_L, and Neo BJAB clones treated with staurosporine (1 μM; Calbiochem) for the times shown. Values express percentages of viable cells calculated as in Figure 1 and represent the mean ± standard deviation of 3 independent experiments.