These immature human FXS astrocytes also secrete uPA more than healthy control astrocytes, and the increased uPA augments tyrosine receptor kinase B (TrkB) phosphorylation within the docking site for phospholipase-Cγ1 (PLCγ1) in cocultured rat primary neurons (Peteri et al., 2021). Here, NTRK2 is linked to fragile X syndrome.