GAS6 and COVID-19: COVID-19 patients with PaO2/FiO2 > 200 had lower plasma GAS6 levels than those with PaO2/FiO2 ≤ 200 (Figure 3D), and optimum cut-off plasma levels of GAS6 < 24 ng/mL detected those more likely to maintain good lung function (PaO2/FiO2 > 200) (Figure 3E).