EGR1 expression is repressed by the recruitment of NAB proteins (NGFI-A binding protein) 1 and 2 through an interaction with EGR1 at its cognate promoter site, establishing a negative feedback loop (Russo et al, 1993; Russo et al, 1995; Svaren et al, 1996; Kumbrick et al, 2005; Kumbrick et al, 2010). NAB proteins interact with the EGR R1 domain through a conserved NCD1 domain (NAB conserved domain 1) and this interaction is abrogated by mutation of EGR residue I293 (Svaren et al, 1996; Russo, 1993). NCD1 is also required for multimerization of the NAB proteins (Savern et al, 1996; Svaren et al, 1998). Two other conserved regions of NAB proteins (NCD2 and CID, for CHD4-interacting domain) are required for the repression function of the proteins (Svaren et al, 1996; Srinivasan et al, 2006). In some contexts, NAB proteins have also been shown to activate EGR-mediated transcription, and EGR- and NAB-dependent transcription is required for peripheral nervous system myelination (Sevetson et al, 2000; Le et al, 2005).