Thermal proteome profiling (TPP) reveals NAMPT as the anti-glioma target of phenanthroindolizidine alkaloid PF403

) in U87 cells. X-ray diffraction and amino acid spot mutation experiments revealed that PF403 primarily relies on the formation of pi-pi interactions with residue Tyr188 to maintain binding with NAMPT (PDB code 8Y55). After NAMPT was knocked down with lentivirus, PF403 lost or partially lost its antitumor activity at the cellular and animal levels. These findings suggest that PF403 exerts antitumor activity by directly targeting NAMPT.