In contrast to this result, loss of ZCCHC11 via siRNA on its own was sufficient to cause regression of established LIN28A-positive tumor xenografts to a similar level as LIN28A knockdown, raising doubts on TUTase redundancy in let-7 repression in LIN28A-positive human cancer cells (Piskounova et al., 2011). This evidence concerns the gene TUT4 and cancer.