ID-like protein inhibitor HLH 1R21 bHLHb25 DNA-binding protein inhibitor ID-3 inhibitor of DNA binding 3, dominant negative helix-loop-helix protein helix-loop-helix protein HEIR-1 inhibitor of differentiation 3 HEIR-1 class B basic helix-loop-helix protein 25 inhibitor of DNA binding 3, HLH protein