Moreover, as discussed above, the fact that a strong expression of AQP5 and HER2 positivity is positively correlated might suggest that some group of BCs which carry HER2 positive, high AQP5 breast cancer, the gene amplification of AQP5 might be suggested as a key driving force for oncogenesis if our findings of AQP5 gene amplification is reproduced in a large number of breast cancer samples. This evidence concerns the gene ERBB2 and breast cancer.