In the breast cancer study a complete analysis of the expression of PDE genes at the mRNA and protein level in established estrogen receptor positive and negative breast cancer cell lines and in patients’ primary breast cancer biopsies by microarray analysis, qPCR, Western blot analysis, immunofluorescence and immunohistochemistry was performed (Dong et al., 2015). This evidence concerns the gene ALDH7A1 and breast carcinoma.