The sequence-specific transcription factor Sp1 binds GC box sequences in the promoters of a variety of genes. The 97 kD Sp1 transcription factor contains two zinc finger domains that determine sequence specificity of binding to the 5'-GGGGCGGGGC-3'. This transcription factor regulates nucleoside, nucleotide and nucleic acid metabolism and many other "housekeeping" genes. Sp1 can be modified by phosphorylation by the upstream kinase ERK1 and has been shown to interact with a large number of proteins. The transcriptional activity of Sp1 has been shown to be disrupted in early Huntington's disease. The Poly6247 antibody recognizes human, mouse, and rat Sp1 and has been shown to be useful for Western blotting.