UBA1 and leukemia: Interestingly, we found that anti-MM LBH589 and anti-leukemia Nilotinib can also induce RNF6 auto-polyubiquitination in the in vitro ubiquitination system that lacks any other enzymes but recombinant human His6-Ubiquitin E1 enzyme (UBE1) and recombinant human UbcH5a/UBE2D1 protein as described by the manufacturer (Boston Biochem Inc).