Effects of JZL184 and CP55,940 upon PC-3 cell proliferation. Cells were incubated for 3 weeks in the absence or presence of EGF (10 ng/ml). Cells in 6 well plates were treated for three weeks without medium change in the absence or presence of 10 ng/ml of EGF. A and B: After two of the three weeks, either vehicle or JZL184 (1 μM) was added to the wells and the incubation was continued for a week without change of medium. In A, levels of 2-AG and N-acylethanolamines are shown. The data, taken for both PC-3 experimental series, show the total levels of the lipids in the cell extract expressed relative to the corresponding value for the extracts taken from wells containing control cells from the same plate. The bars show median values. Abbreviations: 2-AG, 2-arachidonoylglycerol; AEA, anandamide; PEA, palmitoylethanolamide; OEA, oleoylethanolamide; SEA, stearoylethanolamide. In B the data are from the first experimental series, and values are means ± s.e.m., n = 6. **P < 0.01, ***P < 0.001, Šídák’s multiple comparison test vs. the corresponding vehicle control following a significant interaction term in the two-way ANOVA matching for JZL184. In C (first experimental series), the same experimental protocol was followed, but using 100 nM CP55,940 (“CP”). In C, data is given as means ± s.e.m., n = 7 (EGF-treated) or n = 3 (no EGF). **P < 0.01, NSnot significant, Šídák’s multiple comparison test vs. the corresponding vehicle control following a significant interaction term in the two-way ANOVA matching for CP55,940.