To further characterize the role of endothelial Foxf2 in the maintenance of vascular function and examine a possible mediating effect of Tie2 signaling, we pharmacologically modulated Tie2 activity in mice and performed subsequent in vivo analyses together with studies on isolated brain vessels. Specifically, we applied AKB-9778, a selective small molecule inhibitor of vascular endothelial protein tyrosine phosphatase (Ptprb, VE-PTP) previously shown to stabilize the vasculature through Tie2 activation (Saharinen, et al., 2016; Shen et al., 2014). Mass-spectrometry analysis of isolated brain vessels from vehicle-treated Foxf2iECKO and Ctrl mice (Foxf2iECKO-Veh and Ctrl-Veh, respectively) confirmed the dysregulation of multiple proteins related to Tie2 signaling. Treatment with AKB-9778 for 48h restored their levels. Specifically, the abundance of Nos3, Nostrin and Gucy1b1 (implicated in nitric oxide metabolic process), Cldn5, Ctnnd1, Pecam1, and Rap1b (implicated in establishment of endothelial barrier), and Tie2, Flt1, and Itgb1 (implicated in angiogenesis) were all upregulated upon Tie2 activation. Collectively, these findings demonstrate that AKB-9778 rescues the deficiency of Tie2 signaling in mouse BECs lacking Foxf2.