TMPRSS2 and COVID-19: In order to further understand the underlying mechanisms of PPI network-based findings, we investigated the expression levels of the 8 selected stroke-associated genes (VACM-1, SAMHD-1, DDAH-1, HMOX1, LTC4S, ACTB, KPNA2, and JUN) and 4 SARS-CoV-2 host factors/genes (ACE2, TMPRSS2, Furin, and NRP1) between COVID-19 positive patients and negative individuals, respectively (Figure 5).