HDAC9 and COVID-19: Specifically, several Notch-related genes were upregulated in COVID-19 samples for all three organs, including HDAC9, a selective regulator of Notch, FBXW7, a regulator of angiogenesis through Notch (Izumi et al., 2012), and TBLR1, an indirect Notch regulator through degradation (Perissi et al., 2008).