In vitro repression of phage lambda DNA transcription by a partially purified repressor from lysogenic cells.

Abstract
Experiments demonstrated an in-vitro repression of [lambda] mRNA production in a partially purified system. Considering RNA synthesis and binding results together, there appears to be very strong evidence that the cI repressor acts by an inhibition of [lambda] mRNA synthesis. Repressors may also act at the DNA level in bacteria.