Effects of carboxylesterase inhibitors (1 μM) on 2-AG concentrations and cell invasion of PC-3 cells. (A) 2-AG concentrations in PC-3 cells treated with 1 μM of compounds HTFP (1b), OTFP (1c), DETFP (1d), DDTFP (1e), HOA (6a), and OTFPOHSO2 (2b). Values are means ± SEM (n = 3). (B) Cell invasion of PC-3 cells treated with compounds HTFP (1b), OTFP (1c), DETFP (1d), and DDTFP (1e). Cell invasion was normalized to the control cells (as 100%). Values are means ± SEM (n = 12). *Significantly different from control with p < 0.005 and #significantly different from control with p < 0.01.