We used the cytoHubba plugin to find the critical genes in the process of PD pathogenesis and obtained a sub-network containing 10 genes, including ESR1, PTEN, SHC1, IGF1R, SMAD2, KRAS, MDM2, HIF1A, BMP4, and ACVR2B (Figure 5B). The gene discussed is BMP4; the disease is Parkinson disease.