Extended Data Fig. 4: The Prox1 −11 kb enhancer controls Prox1 mRNA levels in lymphatic endothelial cells.

a, Prox1 mRNA levels in E18.5 primary dermal LECs and BECs. Data represent individual litters (5–7 embryos) of each genotype and are shown as mean values ± SD (n = 3 replicates for each litter). b, Prox1 mRNA levels in livers isolated from embryos of each genotype at E18.5. Data shown as mean ± SD, unpaired two-tailed t test with no adjustment for multiple comparisons. c, Immunostaining of liver sections taken from embryos at E14.5 show no differences in PROX1 levels (red). d, Reduction of Prox1 mRNA in LECs (*P = 0.02310) is accompanied by reduced Flt4 (*P = 0.01706) and increased CD34 expression (*P = 0.01705). Data represent average expression in LECs from three independent litters and are shown as mean ± SEM., unpaired two-tailed t test with no adjustment for multiple comparisons. e, Immunostaining of coronal sections of E14.5 embryos demonstrates reduced levels of PROX1 (magenta), LYVE1 (yellow) and VEGFR3 (cyan) in lymphovenous valves (arrows) of mutant embryos compared with wild type littermates. f, Runx1 and Gata2 mRNA levels in primary dermal LECs and BECs isolated at E18.5. Data represent average expression from three independent litters and are shown as mean values ± SEM. *P = 0.0101, ordinary one-ANOVA with Dunnett’s multiple comparisons (where error bars are not shown n = 2). Scale bars, 100 µm (c, e).