Over the past decade, important roles for the 84–88kDa Group VIA Ca 2+ -independent phospholipase A 2 (iPLA 2 β) in various organs have been described. We demonstrated that iPLA 2 β participates in insulin secretion, insulinoma cells and native pancreatic islets express full-length and truncated isoforms of iPLA 2 β, and certain stimuli promote perinuclear localization of iPLA 2 β. To gain a better understanding of its mobilization, iPLA 2 β was expressed in INS-1 cells as a fusion protein with EGFP, enabling detection of subcellular localization of iPLA 2 β by monitoring EGFP fluorescence. Cells stably-transfected with fusion protein expressed nearly 5-fold higher catalytic iPLA 2 β activity than control cells transfected with EGFP cDNA alone, indicating that co-expression of EGFP does not interfere with manifestation of iPLA 2 β activity. Dual fluorescence monitoring of EGFP and organelle Trackers combined with immunoblotting analyses revealed expression of truncated iPLA 2 β isoforms in separate subcellular organelles. Exposure to secretagogues and induction of ER stress are known to activate iPLA 2 β in β-cells and we find here that these stimuli promote differential localization of iPLA 2 β in subcellular organelles. Further, mass spectrometric analyses identified iPLA 2 β variants from which N-terminal residues were removed. Collectively, these findings provide evidence for endogenous proteolytic processing of iPLA 2 β and redistribution of iPLA 2 β variants in subcellular compartments. It might be proposed that in vivo processing of iPLA 2 β facilitates its participation in multiple biological processes.