Transcriptional activator that regulates the cold-induced transcription of CBF/DREB1 genes. Binds specifically to the MYC recognition sites (5'-CANNTG-3') found in the CBF3/DREB1A promoter. Mediates stomatal differentiation in the epidermis probably by controlling successive roles of SPCH, MUTE, and FAMA. Functions as a dimer with SPCH during stomatal initiation (PubMed:18641265, PubMed:28507175). Homodimer (Probable). Efficient DNA binding requires dimerization with another bHLH protein (By similarity). Interacts with the C-terminal part of HOS1 (PubMed:18641265). Heterodimers with SPCH, MUTE, and FAMA (PubMed:18641265, PubMed:28507175). Widely expressed in the whole plant with high expression in leaves and stem. Broad expression within stomatal cell lineages of leaf epidermis. By high-salt stress, cold stress and abscisic acid (ABA) treatment. Ubiquitinated. Cold-treatment induced association with the E3 ubiquitin ligase HOS1 targets the protein for proteolysis by the ubiquitin-dependent proteasome pathway. Sumoylated at Lys-393 by SIZ1. Sumoylated ICE1 represses HOS1 and MYB15 and facilitates the positive regulation of CBF3/DREB1A-dependent cold signaling and freezing tolerance. The ice1-2 scrm2-1 double mutant lacks stomata so that the epidermis only contains pavement cells.