Notably, the PDE5 gene was inversely associated with multiple metastasis suppressor genes (MSGs) (ARHGDIB, BRMS1, CASP8, CD44, CDH2, MAP2K4, MAPK14, PEBP1) in three human breast cancer gene expression cohorts (GSE2034, GSE1456 and GSE26304). The gene discussed is CD44; the disease is breast cancer.