ATM and cervical squamous intraepithelial neoplasia: The results of this study confirmed that the expression of ATM protein in Ect1/E6E7 cells was significantly lower than that in SiHa cells, suggesting that SiHa cells have stronger radiation resistance than Ect1/E6E7 cells, while were inconsistent with others reported that there was no significant difference in the expression of ATM protein between cervical cancer and CIN [39].