Fig 1: Schematic representation of cell death pathways in colorectal cancer (CRC) cells following fenbendazole treatment.Fenbendazole induces G2/M arrest and apoptosis in both (A) 5-FU-sensitive SNU-C5 and (B) 5-FU-resistant SNU-C5 (SNU-C5/5-FUR) CRC cells. In SNU-C5 cells, fenbendazole is presumed to activate p53-mediated apoptosis by increasing p53 expression. In SNU-C5/5-FUR cells, fenbendazole triggers apoptosis without affecting p53 expression, whereas fenbendazole enhances ferroptosis by inhibiting the expression of GPX4 and SLC7A11. Therefore, although fenbendazole has anti-cancer effects on both 5-FU-sensitive and resistant CRC cells, the mechanism of action appears to be different. That is, fenbendazole promotes cell death by activating p53-mediated apoptosis in SNU-C5 cells, whereas by both enhancing p53-independent apoptosis and ferroptosis-augmented apoptosis in SNU-C5/5-FUR cells. PARP, poly (ADP-ribose) polymerase; HMGB1, high mobility group box 1; GPX4, glutathione peroxidase 4; LC3, light chain 3.