PRKG1 and breast cancer: We also found that silencing both Prkg1 and Prkg2, 2 members of PKG, dramatically reduced the CSC-like properties of 4TO7Lung cells, shown by reduced expression of stemness signature genes (Fig 5G–5I) and the side populations in 4TO7Lung cells (Fig 5J and 5K), confirming the importance of cGMP/PKG pathway in regulating the stemness of breast cancer cells.