The MBD family of proteins includes MeCP2, MBD1, MBD2, MBD3 and MBD4. MBD1 (methyl-CpG binding domain protein 1) binds to methylated CpG sites and represses gene transcription. MBD1 is recruited to both methylated and non-methylated CpGs by separate domains: the CXXC domain targets the protein to non-methylated CpGs whereas the MBD domain targets the protein to methylated CpG. MBD1 may also interact with histone methyltransferase SETDB1 to repress transcription.