In addition, NO attenuates TGF-β1-induced myofibroblast differentiation of prostatic fibroblasts which plays a key role in BPH development and prostate fibrosis, via its antagonistic effect to NADPH oxidase 4 (NOX4) and reactive oxygen species (ROS) downstream of TGF-β1 [5]. Here, NOX4 is linked to benign prostatic hyperplasia.