The c-myc protein is a 62 kD nuclear factor that is ubiquitously expressed in the nucleus. c-myc is part of a heterodimeric complex with MAX that acts as a potent transcriptional activator. c-myc is modified by glycosylation and phosphorylation and has been shown to interact with a number of proteins including SMAD2, SMAD3, Pam, cdc6, BRCA1, Mlh1, p34cdc2, MAD, and Sp1. c-myc is extremely labile and is degraded very quickly even in extracts prepared with boiling SDS sample buffer, such that the observed protein size is approximately 41 kD. The 9E10 monoclonal antibody recognizes human myc and the 10 amino acid epitope tag of human c-myc. The 9E10 antibody has been shown to be useful in a number of applications including Western blotting, direct ELISA, flow cytometry, immunoprecipitation, immunofluorescence, immunohistochemistry (paraffin), and immunoaffinity purification of proteins expressing the human c-myc tag.