We investigated the effect of parkin on mitochondrial function and apoptosis in SH-SY5Y, L6, RD, and COS-1 cells. Wild-type parkin attenuated reactive oxygen species (ROS) production in SH-SY5Y cells and mutant parkin enhanced ROS production in SH-SY5Y and L6 cells. Reactive oxygen intermediates, that were detected in mitochondria, were decreased in cells with overexpression of parkin. Parkin prevented apoptosis and enhanced mitochondrial membrane potentials in SH-SY5Y and L6 cells not in COS-I cells. Expressions and enzymatic activities of mitochondrial respiratory chain complexes were not uniformly enhanced but those of complex I were selectively enhanced. The present results suggest the cell-selective function of parkin, i.e., parkin possesses anti-apoptotic and anti-oxidant function in neuronal or myogenic cells but not in kidney cells. (c) 2006 Elsevier Inc. All rights reserved.