CEACAM1 interaction with VEGFR-3 and Prox1. (A) In quantitative RT-PCR analyses, the mRNA level of VEGFR-3 is significantly elevated in CEACAM1-overexpressing HDMECs (CC1) in comparison to those transfected only with empty vector (EVec) and to those transfected for mutated CEACAM1/y− (CC1/y−). The significance was determined applying the Student t test. (B) At the protein level, CEACAM1-overexpressing HDMECs (CC1) exhibit markedly enhanced amount of VEGFR-3 in comparison to HDMECs transfected for CEACAM1/y− (CC1/y−) or empty vector. (C) Interestingly, the CEACAM1-induced (CC1) increase of VEGFR-3 expression in real-time RT-PCR analyses is suppressed significantly by simultaneous transfection of HDMECs for CEACAM1 and Prox1 (CC1 + P-Si) and reduced below the level of control HDMECs transfected only with empty vector. (D) HDMECs overexpressing CEACAM1 (CC1) show enhanced protein amount of Prox1 by approximately 2.5 times in comparison to that transfected with empty vector or for CEACAM1/y− (CC1/y−), as demonstrated here in immunoblotting analysis. The horizontal bars represent assessment of significance, comparing Evec with CC1 or CC1 compared with CC1/y− (A) and Evec compared with CC1 or CC1 compared with CC1 + P-Si (C). *P < 0.5; **P < .01. Error bars represent the standard deviation.