Under such condition EIN2 is activated and is cleaved to release EIN2-C from the membrane-bound EIN2-N portion. The enzyme that causes the cleavage is yet unknown.[2] The role of EIN2-N is also unknown in A. thaliana. But in rice, its homologue OsEIN2-N (Os for Oryza sativa, the scientific name for rice) interacts with another protein, mao huzi 3 (MHZ3), a mutation of which gives rise to insensitivity to ethylene.[33]