HSPA4 and proteostasis deficiencies: Additional potential pathogenic involvement of Hsp70 in protein misfolding diseases was shown by Fontaine and colleagues: Hsp70 in complex with its co-chaperone J-protein DnaJC5 controls the extracellular release of disease-associated proteins like tau, α-synuclein, and transactive response DNA-binding protein 43 (TDP-43), providing a mechanism for how aggregation-prone proteins are able to leave the cell and possibly propagate [20].