New insights have highlighted the importance of the Ras homolog gene family (RhoA)–Rho-associated protein kinase (ROCK) pathway in maintaining a flaccid penile state; notably, the inhibition of RhoA–ROCK signalling is able to improve ED, even when associated with hard-to-treat causes, such as diabetes, suggesting that RhoA–ROCK could represent a new therapeutic target [157]. This evidence concerns the gene RHOA and diabetes mellitus.