Immunohistochemistry: an important application of monoclonal as well as polyclonal antibodies to determine the tissue distribution of an antigen of interest in health and disease. IHC is widely used for diagnosis of cancers; specific tumor antigens are expressed de novo or up-regulated in certain cancers. The IHC technique is routinely used as an important tool in health care and pathology for e.g. diagnostic purposes or to stratify patients for optimized treatment regimes. IHC is also widely used in research where molecules of interest are analyzed to study their roles in both healthy and diseased cells and tissues on the molecular, cellular or tissue level.