Skp2 inhibitor 3 (E35), an antitumor agent, is a potent S‑Phase Kinase-associated Protein 2 (SKP2) inhibitor, with an IC 50 of 4.86 μM for Skp2-Cks1 binding. Skp2 inhibitor 3 (E35) significantly inhibits colony formation and migration, as well as arrests the cell cycle at the S-phase.