- Multiple factors bind the upstream activation sites of the yeast enolase genes ENO1 and ENO2: ABFI protein, like repressor activator protein RAP1, binds cis-acting sequences which modulate repression or activation of transcription. Brindle, P.K., Holland, J.P., Willett, C.E., Innis, M.A., Holland, M.J. Mol. Cell. Biol. (1990)