To explore the molecular mechanism involved in the function of Msi1 on the cell cycle of cervical cancer cells, the mRNA levels of several key cell cycle regulators (p21, p27, p53, CDK2, cyclinA and cyclinD1) were examined by Real-Time PCR in Msi1-overexpressing and Msi1-knockdown cervical cancer cells (HeLa-Msi1, SiHa-Msi1, HeLa-shMsi1 and SiHa-shMsi1 cells) as well as in the control cells (HeLa-EGFP, SiHa-EGFP, HeLa-shControl and SiHa-shControl cells). The gene discussed is CDKN1B; the disease is cervical carcinoma.