RARA and acute promyelocytic leukemia: Very recently, it has been found that As2O3 induced APL cells differentiation occurs as a result of direct binding of As2O3 to cysteine residues of zinc fingers in the RING finger-B Box-Coiled Coil (RBCC) domain of PML-RARα fusion protein, which results in enhanced SUMOylation/Ubiquitination and then degradation of PML-RARα fusion protein, promoting cell differentiation leading to clinical remission.