Furthermore, bisulfite sequencing on the promoter of long interspersed nuclear element 1 (LINE1) which is a retrotransposon [27] revealed that the methylation was not much reduced for both short-term and long-term UHRF1 knockdown compared with control knockdown (Figure 3D), suggesting that maintenance methylation in retinoblastoma cells is not severely affected by UHRF1 depletion. Here, UHRF1 is linked to retinoblastoma.