PDE4D and neoplasm: The 31 genes known to act within the EGFR/Ras/MAPK pathway included the ERBB receptor ligands NRG1 and NRG3, the tumor suppressor microRNA mir-31, FOXP1, PARD3, PDE4D, PTPRG, RGS6, TRPS1, VMP1, and components of the glutamate transport system.