Recombinant proteins are proteins encoded by recombinant DNA that has been cloned in an expression vector that supports expression of the gene and translation of messenger RNA. Modification of the gene by recombinant DNA technology can lead to expression of a mutant protein. Recombinant proteins are useful tools in understanding protein-protein interactions. Recombinant proteins have proven performance in several laboratory techniques, such as ELISA, western blot and immunohistochemistry (IHC). Recombinant proteins are used to develop enzymatic assays. When used in conjunction with a matched antibody pair, recombinant proteins can be used as standards in ELISA, and as positive controls in western blots, and IHC. Recombinant proteins serve as valuable tools for investigating cellular response to stress, and disease situations. Recombinant proteins and peptides administered to animal models of disease assist researchers in identifying novel potential therapeutic candidates.