identification of defective er and subclassifying er + breast cancers on the basis of the presence of defective er is described as a tool potentially useful , as previously shown by the results of a pilot study , for predicting which among the er + tumors will respond and which will fail to repsond to hormonal modes of therapy . improvements are introduced in the specimen sampling and ligand introduction steps of the immunohistochemical procedure which was developed for sub - classifying estrogen receptor - positive tumors of human breast cancers and other cancers of the estrogen target organs on the basis of the presence of defective estrogen receptors . additionally , a new monoclonal antibody reagent which has potential use as a replacement for the polyclonal anti - er antibody reagents is also described . the modified steps include the use of tumor imprints instead of cryosections ; use of ligand coated slides instead of the original ligand layering step . both these modifications which simplified the execution of the test procedure and the availability of a suitable monoclonal antibody reagent should facilitate wider use and automation of the entire procedure if needed . methodology for the application of this modified test procedure for rapidly screening drug compounds to detect which affect the translocation behaviour of defective er and as a simple tool for identifying the presence of components in water and other solutions which might be toxic to the normal non - defective estrogen receptors found in normal tissues are also presented .