FGF20 and Parkinson disease: Niu et al. protected a rat model of 6-OHDA-induced PD by focusing ultrasound-guided systemic administration of recombinant human FGF-20 proteolipids by fusing small ubiquitin-associated modifier (SUMO) to rhFGF-20 to enhance the efficiency of its soluble expression (Niu et al., 2018).