CDKN1B and cancer: Indeed, miR-221/222 has been identified to directly target the Cdk inhibitor p27Kip1 in glioblastoma cells,72 which was further confirmed in other cancer cell lines and primary tumor samples.73–75 Ectopic expression of miR-221/222 accelerated cell proliferation, whereas their suppression induced G1 cell-cycle arrest in cancer cells.