Calcium-independent iPLA2s belong to group VI of the phospholipases A2 (PLA2s), which are implicated in the deacylation/reacylation cycle of membrane phospholipids in cells (Lands cycle). Whereby phospholipids are cleaved by iPLA2s in the sn-2 position, generating lysophospholipids and free fatty acids. However group VI iPLA2s have no substrate preference for arachidonic acid (AA) and their catalytic activity does not require Ca2+. The generated lysophospholipid serves as an acyl-acceptor, appropiated for the incorporation of AA into cellular phospholipids. Moreover, released arachidonic acid can be converted into prostaglandins. An inhibiting effect of group VI iPLA2s by PBEL [3-(1-pyrenyl)-6-(E)-(bromomethylene)-tetrahydropyran-2-one] was suggested. PBEL is a fluorescent substance, synthesized according to a modified and optimized chemical synthesis method of Daniels et al. for bromoenol lactone (BEL). The inhibitory properties of PBEL on iPLA2 activity was carried out by a [1-14C]AA incorporation essay into phospholipids of L929-cells and by a prostaglandin determination of MC3T3-E1/B cells under calcium free conditions. L929-cells, pre-treated with PBEL and [1-14C]AA showed an inhibition effect in form of a decreased exogenous [1-14C]AA incorporation into phospholipids. This result was additionally verified by a significant increase of prostaglandin synthesis of MC3T3-E1/B cells, pre-treated with PBEL and AA. This study also focused on the determination of the intracellular localisation of group VI iPLA2s by PBEL. L929 and MC3T3-E1/B cells, pre-treated with PBEL showed an intracellular fluorescence, visualized by inverse fluorescence microscopy. This result reveals that PBEL was taken up by the cells and that an interaction between PBEL and iPLA2 appeared, detectable by its high fluorescence.