The MBD family of proteins includes MeCP2, MBD1, MBD2, MBD3 and MBD4. MBD2 is highly similar to MBD3 but only MBD2 targets the MeCP1 complex to methylate DNA. MBD2 has two isoforms, MBD2a and MBD2b. MBD2a is a 414 amino acids protein, whereas MBD2b lacks the 152 amino acids N-terminal extension. MBD2a interacts with RNA helicase A to enhance CREB-dependent gene exptression.