PPIA and amyotrophic lateral sclerosis: Furthermore, hnRNPA2B1 interacts with another RNA-binding protein, TDP-43, whose presence in protein inclusions is a hallmark of ALS and frontotemporal dementia, and with PPIA, a biomarker of ALS and a key regulator of TDP-43 function (Nardo et al., 2011; Lauranzano et al., 2015).