CDKN1B and cervical cancer: However, after being transfected with the p27–1 and p27–2 mutant vectors, the luciferase activities lost significant differences between the Msi1 over-expressing SiHa and HeLa cells and their control cells, suggesting that Msi1 might repress p27 translation by occupying the p27–1 and/or p27–2 sequences in cervical cancer cells.