CA9 is a widely-used intrinsic hypoxia marker [22, 23, 33, 36, 39–42], and we and others have demonstrated its correlation with hypoxia in cervix cancer cell lines [35, 36], although it has recently been reported that CA9 expression does not correlate with pimonidazole staining in two cervix cancer xenograft models [43]. This evidence concerns the gene CA9 and cervical cancer.