Mediates stomatal differentiation in the epidermis probably by controlling successive roles of SPCH, MUTE, and FAMA (PubMed:18641265). Functions as a dimer with SPCH during stomatal initiation (PubMed:18641265, PubMed:28507175). Homodimer (Probable). Heterodimers with SPCH, MUTE, and FAMA. Expressed constitutively in roots, leaves, stems, and flowers. Broad expression within stomatal cell lineages of leaf epidermis, except in mature guard-cells. The ice1-2 scrm2-1 double mutant lacks stomata so that the epidermis only contains pavement cells.