Although there was large interpersonal PAI-2 staining variation, our immunofluorescence data provides the first evidence that a fraction of endogenous PAI-2 is found co-located with APP (or aggregation-prone proteoforms) in the placenta of preeclampsia patients, which is consistent with the notion that PAI-2 may preferentially bind to misfolded APP proteoforms in vivo. This evidence concerns the gene APP and preeclampsia.