Abstract: Recent studies have identi?ed speci?c microRNAs that regulate classic cell-cycle control pathways by directly targeting proteins such as E2F transcription factors, cyclin-dependent kinases (Cdks), cyclins and Cdk inhibitors, and have documented that the loss or gain of miRNA-mediated cell-cycle control contributes to malignancy. This review summarizes experimental strategies for miRNAs research and recent progression on the involvement of miRNAs in cell cycle regulation and tumorigenesis.