Antibodies against the Glu-Glu epitope tag typically recognize the short peptide sequence, EMYMPE. The tag originates from the sequence, Glu-Glu-Glu-Glu-Tyr-Met-Pro-Met-Glu, representing a portion of the middle T antigen of polyomavirus, considered to be important in cellular transformation. Antibodies targeting the Glu-Glu epitope may be a useful tool in immunological investigations of Glu-Glu-tagged proteins.