This document discusses molecular docking using multiple receptor conformations (MRC) to address receptor flexibility, one of the major challenges in docking. It notes that while ligand flexibility has been addressed, receptor flexibility remains difficult. The document outlines different approaches to incorporate receptor flexibility in docking and explains that MRC docking uses multiple predetermined receptor structures to represent flexibility. However, it also warns that too many MRCs could increase false positives in virtual screening. The key to successful MRC docking is using a representative set of binding site conformations without unnecessary artifact structures.