ROBO2 and COVID-19: Furthermore, plasma IL-8, IL-6, TNFRSF11B, and CSF EZR levels were allied to severe COVID-19 using the ordinal backward and best linear model21,22,27–29, whereas plasma 4E-BP1 and CSF levels of PD-L1, BMP-4, CLEC10A and ROBO2 withstanded using one model only30–34.