As the top-ranking PPI hub nodes (the MAC-1 subunits ITGAM and ITGB2) were both located in cluster 2 and the leukocyte integrin MAC-1 has a well-recognized role in atherosclerosis (Aziz et al., 2017; Ramos et al., 2018), we chose to focus on MAC-1 protein interactors within cluster 2 to identify key regulators in PAD (Figure 1A; Supplementary File S4). The gene discussed is ITGB2; the disease is peripheral arterial disease.