Colocalization of the GFP signal with various lymphatic markers throughout development. Whole-mount staining of dermal lymphatics in Prox1-GFP transgenic embryos (E14.5) against CD31 (A-C), Prox1 (D-F), and LYVE1 (G-I) show that GFP expression is colocalized with the expression of Prox1 and LYVE1. Moreover, staining of skin cross section of newborn pup (P1) against CD31 (J-L) and podoplanin (PDPN, M-O) specifically found GFP signal in lymphatic endothelial cells, suggesting a lymphatic-specific expression of GFP. (P-R) *Podoplanin staining of a cross section of Prox1-GFP embryo at E10.5 shows the budding LECs (arrows) from the embryonic cardinal vein. Scale bars represent 100 μm with an exception (G-I, 50 μm).