The gene (uniprot ID = A0A0A8KA17) of MDM2 (residues 6-125 for wild type and mutants) was inserted into a pET20b plasmid (ampicillin-resistant) with a six-His-tag in the C-terminal sequence. Proteins were produced in Escherichia coli strains C41 (DE3), C43, and BL21 (DE3), grown in LB broth for non-labelled proteins, and minimal medium supplemented with NH4Cl and/or 13 C6-glucose for labelled proteins. Purification was performed using IMAC (Immobilized Metal Ion Chromatography-5 mL) followed by size-exclusion chromatography).