The mouse immunoglobulin heavy-chain gene enhancer contains sequences that inhibit transcription in vitro in HeLa cell extracts.

The effect of the cell-specific mouse immunoglobulin heavy-chain gene (IgH) enhancer on transcription from heterologous promoter elements was studied in vitro with a HeLa whole-cell extract. No stimulation of transcription could be seen under conditions in which an activation was observed with the simian virus 40 enhancer. We found, however, that a specific segment of the IgH enhancer region contains sequences which inhibit transcription in vitro.