Fig 1: Cellular thermal shift assay (CETSA) shows target engagement for 10 µM HUP-55 on PREP in HEK-293 cells (A). HUP-55 at 1 or 10 µM concentration does not inhibit close relative enzymes FAP, DPP4, DPP9, or DPP2 (B). In HEK-293 cells, HUP-55 decreases aSyn dimerization (C), but when PREP is not expressed (PREP knock-out (KO) HEK-293 cells), no such effect is seen (D). A similar effect was seen in autophagy when assayed with LC3BII protein levels in HEK-293 (E) and PREP-KO HEK-293 cells (F), indicating a PREP-mediated effect. Data are presented as mean + SEM. **, p < 0.01; student’s t-test.