o address the question of ligand entry process, we report targeted molecular dynamics simulations of the entry of the flexible ionic ligand GW0072 in the ligand binding domain of the nuclear receptor PPAR gamma. Starting with the ligand outside the receptor the simulations led to a ligand docked inside the binding pocket resulting in a structure very close to the holo-form of the complex. The results showed that entry process is guided by hydrophobic interactions and that entry pathways are very similar to exit pathways. We suggest that TMD method may help in discriminating between ligands generated by in silico docking. (C) 2011 Federation of European Biochemical Societies.