The present invention discloses modified Hdm2 proteins that are soluble. In addition, the present invention discloses nucleic acids that encode the modified Hdm2 proteins of the present invention. The invention also provides crystals of modified Hdm2 proteins that are suitable for X-ray crystallization analysis. The present invention also discloses methods of using the modified Hdm2 proteins and crystals thereof to identify, select and/or design compounds that may be used as anticancer agents. The present invention further discloses compounds that bind to modified Hdm2 proteins in protein-ligand complexes.