Table 1.

Characterization of staurosporine-induced homotypic aggregation with metabolic inhibitors

	Aggregation (% of control: mean±s.e.m.)
	Staurosporine	PMA
Deoxyglucose	21.0±3.9**	27.4±3.2**
Cycloheximide	97.5±8.0	15.2±5.1**
Colchicine	30.1±5.0**	22.5±2.6**
EDTA	95.7±5.9	NT
Cytochalasin B	18.9±1.8**	15.6±1.9**
4°C	6.1±0.5**	5.9±0.8**

U937 cells were treated with staurosporine (100 nM) or PMA (80 nM) for 3 or 12 h, respectively. The metabolic inhibitors (deoxyglucose (10 mM), cycloheximide (10 μg ml⁻¹), colchicine (10 μM), EDTA (2 mM) and cytochalasin B (1 μM)) were added 1 h prior to the aggregation agonists and remained in the culture. Results are expressed as aggregation relative to control cultures in the presence of the aggregating agonist, but absence of inhibitor (mean±s.e.m., three independent experiments). In all, 47% of U937 cells aggregated in the presence of staurosporine alone, and 56% aggregated in the presence of PMA alone. Aggregation in medium alone was always less than 8%. All values which differ significantly from 100% (Student's t-test, P<0.01) are indicated by asterisks.