EMSA probes were generated by annealing the following complementary oligonucleotides: APO-Sp1/3, 5′- CCAGCTGGGCGGGACCACCAGGGGAGGGGC-3′ and 5′-GCCCCTCCCCTGGTGGTCCCGCCCAGCTGG-3′; APO-Sp1/3mut, 5′- CCAGCTGTTCGGGACCACCAGGGGAGGGGC-3′ and 5′- GCCCCTCCCCTGGTGGTCCCGAACAGCTGG-3′ according to standard procedures.