Proposed model for the balance between the different aggregation states of hIAPP in an aqueous solution. Once hIAPP oligomers are dissolved in an aqueous solution, IAPP intermediate structures (protofibrils) further assemble into amyloid fibrils. Alternatively, they may form toxic membrane-perforating toxic oligomers (top). In the presence of rifampicin, formation of amyloid fibrils is inhibited, but the formation of toxic oligomers is unaffected, consistent with continued cytotoxicity (bottom). This figure originally appeared in an article by J. J. Meier et al.: Am J Physiol Endocrinol Metab 291:E1317–E1324, 2006 (153). It is used with permission from the American Physiological Society.