 Slight improvements have been observed in cases where significant restraints were used during the simulation.The two most common and large-scale sources of error in homology modeling are poor template selection and inaccuracies in target-template sequence alignment.Controlling for these two factors by using a structural alignment, or a sequence alignment produced on the basis of comparing two solved structures, dramatically reduces the errors in final models; these "gold standard" alignments can be used as input to current modeling methods to produce quite accurate reproductions of the original experimental structure.