ID PROTEINS CONTROL GROWTH INDUCTION IN MAMMALIAN-CELLS

Id1, Id2, and Id3 (HLH462) dimerize with members of the basic helix-lo op-helix protein family, but due to the absence of the basic region, t he resulting heterodimers cannot bind DNA. Therefore Id-type proteins negatively regulate DNA binding of the basic helix-loop-helix proteins . Here we report that Id1, Id2, and Id3 are induced shortly after seru m stimulation in arrested NIH 3T3. Antisense oligonucleotides against the Id mRNAs delay the reentry of arrested cells into the cell cycle e licited by stimulation with serum or growth factors. Antisense oligonu cleotides against all three Id mRNAs are more effective than individua l ones. Combined, these results indicate that Id proteins are involved in the control of growth induction.