. . . . "These conditions can be interpreted as: (i) A and B do not dimerize, (ii) A and B cannot both be bound to the DNA at the same time, perhaps because their binding sites overlap, (iii) there is not transcription if neither A nor B are bound to the DNA, (iv) there is a certain balance between the production and decay rates of mRNA and protein, and (v),(vi) either A and B bind to the DNA comparatively" .