Abstract: The present invention provides an anticancer drug having a Ras function inhibitory action. The present invention provides a Ras function inhibitor comprising a compound represented by the formula (I?): wherein each symbol is as defined in the present specification, or a salt thereof.

Abstract: The present invention provides an anticancer drug having a Ras function inhibitory action. The present invention provides a Ras function inhibitor comprising a compound represented by the formula (I?): wherein each symbol is as defined in the present specification, or a salt thereof.

Abstract: Provided is a screening method for a more effective Ras inhibitor. Further provided are amino acid residues at a site important for an interaction with a Ras inhibitor in a Ras polypeptide. By confirming a difference between structural information on the Ras polypeptide by NMR and structural information between a complex of the Ras polypeptide and a seed compound by NMR, a more effective lead compound than the seed compound can be selected. As a result of analysis based on the structural information on the Ras polypeptide by NMR, the amino acid residues capable of interacting with a Ras inhibitor candidate (a) are K5, E37, D38, S39, L56, E63, Y64, A66, M67, Q70, Y71, R73, and T74 with reference to an amino acid sequence set forth in SEQ ID NO: 1.

Abstract: An object of the present invention is to provide a co-crystal of a Ras polypeptide which adopts a conformation having a pocket on the molecular surface of Ras and GTP or a GTP analog, a production method for the crystal, and a screening method for a Ras function inhibitor based on information about the conformation obtained by X-ray crystallographic analysis using the crystal. The object is achieved by focusing on a mutation which adopts a conformation having a pocket on the molecular surface of Ras, acquiring a mutant Ras polypeptide having introduced therein such mutation, producing a co-crystal of the mutant Ras polypeptide and a GTP analog, and further subjecting the co-crystal to X-ray crystallographic analysis to acquire structural information about the conformation including information about the structure surrounding the pocket.