By analyzing ovarian cancer datasets with the cBioPortal (Fig. 1B), we found the highest frequency of AE2 (SLC4A2) gene amplification (TCGA Provisional, 10.0%; TCGA 2011, 4.4%), as compared to AE1 (SLC4A1) (TCGA Provisional, 0.3%; TCGA 2011, 0.3%) and AE3 (SLC4A3) (TCGA Provisional, 2.6%; TCGA 2011, 0.6%). Here, SLC4A2 is linked to ovarian cancer.