CDKN1B and cervical cancer: However, in SiHa-Msi1 cells, Msi1 protein kept a strong binding at 3′UTR binding sites of p21, p27–1 and p53–1; but kept a relatively weak binding at the sites of p27–2 and p53–2, suggesting that Msi1 may have the different effects on target genes in different cervical cancer cell lines.