Phosphodiest-eraseδ (PDEδ) has been revealed to promote effective KRas-4B signaling by sequestering KRas-4B-FMe from the cytosol by binding the prenylated HVR and help to enhance its diffusion to the PM throughout the cell, where it is released to activate various signaling pathways required for the initiation and maintenance of cancer [40,41,42,43], hoping to identify a panel of novel PDEδ inhibitors. Here, PDE6D is linked to cancer.