Perforin oligomers form arcs in cellular membranes: a locus for intracellular delivery of granzymes. by Metkar, S, Marchioretto, M, Antonini, V, Lunelli, L, Wang, B, Gilbert, R, Anderluh, G, Roth, R, Pooga, M, Pardo, J, Heuser, J, Serra, MD, Froelich, C