MAPT and frontotemporal dementia: While nitration of Y18 and Y197 is observed in AD brains and age-matched controls, nitration at Y29 appears to be specific for AD and Pick's disease.182–184 Y197 is also endogenously nitrated in mouse brain samples and PC12 cells as models for AD.185 Single-site nitration of Y18 inhibits tau aggregation in vitro.182 Effects of nitration were also evaluated in vitro through addition of RNS such as peroxynitrite.