FOXO3 and cervical cancer: In addition, when comparing the expression of FOXO3a mRNA in the primary cervical epithelial cells (HCxECs) to several kinds of cervical cancer cell lines with HPV infection (HPV16-positive CaSki and SiHa cells; HPV18-positive HeLa cells) and without HPV infection (C-33A cells), regardless of whether the cells had an HPV infection or not, all cervical cancer cells had downregulated expression of FOXO3a mRNA.