Immunogen sequence: MKAVSPVRPS GRKAPSGCGG GELALRCLAE HGHSLGGSAA AAAAAAAARC KAAEAAADEP ALCLQCDMND CYSRLRRLVP TIPPNKKVSK VEILQHVIDY. ID4 is transcription factors containing a basic helix-loop-helix (bHLH) motif regulate expression of tissue-specific genes