The structure of the ONC201−HsClpP complex wasdetermined at 2 Å resolution. Similar to ADEP and D9,ONC201 binds noncovalently to the highly complementary hydrophobic pockets formed between neighboring HsClpP subunits (Figure 4Aiv). Notably, binding of ONC201induces widening of HsClpP’s axial pore (Figure 4Aiv), while the complex adopts a compact conformation (Figure 4Biv) that highly resembles that of ADEP and D9 binding. As with D9, the axial loops in the ONC201−HsClpP complex are not resolved in the crystal structure (Figure 4Biv,Ciii)