Interacts with EP300 and acts as a repressor of MYOD-dependent transcription and muscle differentiation. Inhibits EP300 histone acetyltransferase activity. Acts as a repressor of TGFB/SMAD transcriptional responses. May act as a repressor of the TGFB/SMAD3-dependent signaling by selectively blocking formation of TGFB-induced SMAD3-SMAD4 complex. Heterodimer with EID2B. Interacts with the C-terminus of EP300. Interacts with HDAC1 and HDAC2. Interacts with SMAD2, SMAD4 and with the MH2 domain of SMAD3. Most abundantly expressed in placenta. Highly expressed in liver, brain, heart, skeletal muscle, and kidney. The N-terminal portion of EID2 is required for nuclear localization.