Altered Sonic hedgehog signaling is associated with morphological abnormalities in the penis of the BB/WOR diabetic rat.
http://www.ncbi.nlm.nih.gov/pubmed/12748119 <<Basically without SSH you get ED is the spirit of these implications… So with it would you build smooth muscle yet break down collagen?
Unique functions of Sonic hedgehog signaling during external genitalia development.
http://www.ncbi.nlm.nih.gov/pubmed/11684660 <<< Further reveals the role of SHH in penile development along with the other indicated factors such as BMP-4, and Fgf, ie if you take SHH away bad things happen for the penis or good things never will at least, which is bad.
Molecular analysis of external genitalia formation: the role of fibroblast growth factor (Fgf) genes during genital tubercle formation. http://en.wikipedia.org/wiki/Genital_tubercle
http://www.ncbi.nlm.nih.gov/pubmed/10804187 <<< However, the abnormal external genitalia development of Fgf10(-/-) perinatal mice suggested the importance of Fgf10 in the development of the glans penis and the glans clitoridis. These results suggest that the FGF system is a key element in orchestrating GT development.
SHH inhibition in the penis induces apoptosis and ED, and SHH treatment at the time of CN injury suppresses smooth muscle apoptosis and promotes regeneration of erectile function.