Band shift analysis. A. Oligonucleotides used in EMSA and mutagenesis studies of the hTERC promoter. The sequence of the wild type oligonucleotides covering identified transcription factor Sp1.2 binding sites are shown as h41. The colon symbol represents bases identical to those in the top row, the mutant sequences are shown underneath. B. Single mutation in Sp1.2 site inhibits the Sp1 binding activity. 5637 nuclear extract was mixed with radiolabelled oligonucleotide probe and analysed by EMSA. Specific DNA/protein complexes are indicated by the arrow on the right hand side. The oligonucleotide h41 was used as a probe and the oligonucleotides used as competitors are indicated at the top oflanes 2–5.