PPIA-IN-1 (Compound 20b) is an inhibitor of peptidyl-prolyl isomerase A (PPIA) with a KD of 0.52 μM. It demonstrates antiproliferative activity across various cancer cell lines, including an IC50 of 0.69 μM in HCT116 cells, induces cell cycle arrest at the G0/G1 phase, and exhibits antimetastatic effects in HCT116 cells. PPIA-IN-1 elevates ROS levels, causing DNA damage, ER stress, and mitochondrial dysfunction, and induces apoptosis in HCT116 cells via the MAPK pathway. Additionally, PPIA-IN-1 shows antitumor activity in a CT26 xenograft mouse model.