For instance, the designed insulin-derived polypeptide insulin-derived polypeptide (SHI), capable of donating H2S, reduced α-synuclein levels, increased dopamine transporter (DAT) expression, and improved behavioral outcomes in Drosophila and C. elegans Parkinson’s disease models (Figure 4, Table 4) [104]. The gene discussed is SLC6A3; the disease is Parkinson disease.