Top panels: whole-mount immunofluorescence of E18 Foxc2flox/flox;Prox1-CreERT2 and littermate control mesenteries, showing downregulation of FOXP2 in Foxc2 deficient vessels. Bottom panels: extraction of nuclear FOXP2 staining (grey) using IMARIS surface mask generated based on PROX1 staining (green). Unmasked FOXP2 staining is shown in magenta. Quantification of FOXP2 levels in mesenteric lymphatic vessels of Foxc2flox/flox;Prox1-CreERT2 and control littermates based on nuclear FOXP2 signals as in (B) (n = vessels [mice], as indicated). 