A. EMSAs showing in vitro DNA interaction of recombinant BES1 and/or HSFA1 with HSE-containing fragments of the HSP70.3 and HSP90.1 promoters. Unlabeled competitor fragments with functional HSEs (C1 +HSE) or mutated versions (C2 -HSE) were used for competition studies in 100x molar access (lanes 6 and 7). 