EMSA analysis
EMSA kit (Invitrogen, E33075) was used to perform EMSA analysis. The oligonucleotide probes were synthesized (listed in Table S2) and annealed. The protein-free sample was used as blank control. The mass ratios of the probe and protein were 1:5/1:15/1:50 in each reaction mixture (10 μL). ChemiDoc XRS+ system (Bio-Rad, USA) was used to observe the gels on a 490 nm SYBR photographic filter.