Regulation of FLAP mRNA expression by PGE2 and NS-398 in normal and osteoarthritis osteoblasts. Confluent cells were incubated for their last 48 hours in Ham's F12/DMEM medium containing 0.5% BSA in the presence or absence of 500 nM prostaglandin E2 (PGE2) or 10 μM NS-398. 5-Lipoxygenase-activating protein (FLAP) expression was measured as described in the legend to Figure 2. Values are means ± SEM; p values compare data with basal values in each group. Normal samples, n = 3; low and high osteoarthritis (OA), n = 5 for each group. GAPDH, glyceraldehyde-3-phosphate dehydrogenase.