A549-ACE2 cells were plated in DMEM high-glucose, 10% fetal bovine serum, 1X non-essential amino acids, and 2 mM L-glutamine on a 384-well plate at a seeding density of 2000 cells/well and allowed to adhere overnight. Cells were treated with 1 or 10 µM of a PIKfyve inhibitor, 0.01% DMSO (negative control), or 10% DMSO (positive control) for 48 hours. CellTiter-Glo reagent (Promega) was added to each well and luminescence was detected using a GloMax plate reader (Promega). Two biological replicates of each treatment in quadruplicate were analyzed. Raw data was used to calculate cell viability according to the following formula: ((raw RLU value -average of positive control wells)/(average of negative control wells -average of positive control wells))*100. GraphPad Prism was used to generate all plots, and the data included in Tables and Figure .