In the absence of ligand, the RARs are bound by corepressors and the expression of target genes is silenced. Corepressors interact with a hydrophobic groove in the receptors via their LxxH/IIxxxI/L or corepressor (CoRNR) motif. The repressors also act as adaptors to recruit other protein complexes. For more details check PMIDs 20084085 and 19471584. The two repressors are listed with aliases in parentheses, full names and links to gene report pages:

Ncor1 (N-CoR, N-CoR1) – nuclear receptor co-repressor 1
Ncor2 (N-CoR2, Smrt) – nuclear receptor co-repressor 2