Furthermore, we have identified two trans-acting regulatory factors that bind to the initiator element- the multifunctional regulatory factor, YY1 (Breen et al. , 1996) and USF2 (Breen and Jordan , 1998).
Expression of YY1 together with USF2 dramatically reduces the level of activation of the ATPA initiator element relative to transfection of USF2 alone (Breen and Jordan , 1998).