Isoindolinone seed compounds 15 and optimised analogues 16 inhibit the p53–HDM2 interaction. The modelled binding mode, based on the pharmacophore model presented (Hardcastle et al., 2005), of compound 16c (solid sticks) in the p53 peptide (F19, W23, L26 side chains shown as thin sticks) binding pocket of HDM2 (surface, from PDB # 1YCR) is shown on the right.