For endogenous co-immunoprecipitations, MEL nuclear extracts were diluted to reach 100mM KCl salt concentration using Heng 0 buffer (20mM HEPES KOH pH7.9, 20% glycerol, 0.25mM EDTA, 0.05% Np40). For co-IP experiments in MEL cells, 0.5 mg nuclear extract was used per IP. Extracts were treated with 1U Benzonase nuclease (Millipore). For RNA-seq, total RNA was extracted from MEL or E13.5 sorted fetal liver populations using the RNeasy mini kit (Qiagen). Libraries were prepared according to Illumina's standard instructions