ABCG2 and cervical intraepithelial neoplasia: This study found that the expression of ABCG2 protein in Ect1/E6E7 cells was slightly higher than that in SiHa cells, while other studies reported that the expression of ABCG2 protein in cervical cancer was significantly higher than that in cervical intraepithelial neoplasia (CIN) tissue [34, 35].