RNase treatment relieves poly(G)-mediated inhibition of c-Myb DNA-binding. NR1R2R3 and R2R3 were incubated with the MRE-containing DNA probe in the presence of 20 ng poly(G) homoribopolymer (lanes 3 and 4). The sample shown in lane 4 was in addition incubated with 2000 U RNase T1. To allow for RNase T1 mediated degradation of poly(G), all samples were incubated for 30 minutes at 37°C prior to addition of Myb-protein mixture. Binding reactions were subsequently incubated for 15 minutes at 25°C and analyzed by EMSA and phosphorimaging. Lanes 1 and 2 show free probe and binding reaction without homoribopolymer addition, respectively.