Figure 4.

Staurosporine-induced aggregation is inhibited by inhibitors of both conventional and novel PKC isotypes. U937 cells were incubated with various PKC inhibitors in the presence or absence of staurosporine (100 nM, 4 h) or PMA (80 nM, 12 h). Inhibitors were added 1.5 h prior to the agonists. (a) The inhibitors were added at the concentrations shown. Aggregation is expressed as a % of the aggregation obtained in the absence of inhibitor. PMA aggregation is shown in the presence of the highest concentration shown for each inhibitor. The figure shows the mean±s.e.m. of three experiments, and values that differ significantly from control (i.e. no inhibitor) (ANOVA with post hoc Dunnett's, P<0.05) are indicated by an asterisk. Aggregation in medium alone was less than 8%. (b) Representative images of aggregation in the presence of staurosporine (100 nM) alone (panel 1), staurosporine and calphostin C (500 nM; panel 2), staurosporine and Gö6976 (500 nM; panel 3) and staurosporine and rottlerin (10 μM; panel 4). Images of cells in culture point were obtained using an inverted-phase contrast microscope, attached to a video camera, and captured using NIH image software.