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![Activation of the cGMP/protein kinase G system in breast cancer by the dopamine receptor-1](https://image.oaes.cc/aad43cfc-e6c6-4871-9005-905c6b18a9b2/3266.fig.3.jpg)
Figure 3. Characteristics of the cGMP/protein kinase G (PKG) pathway. Soluble guanylate cyclase (sGC) is activated by nitric oxide (NO) and by three drugs, namely Riociguate, YC-1, and Bay 41-2271, and is inhibited by ODQ. Activated sGC converts GTP to cGMP while phosphodiesterase 5 (PDE5) hydrolyzes cGMP to 5’GMP. PDE5 inhibitors include tadalafil (Cialis), sildenafil (Viagra) and vardenafil (Levitra). Elevated cGMP activates PKG, which affects many important targets