VEGFA and lentivirus infection: VEGFR2-WT, VEGFR2 K1270R (a form that cannot be SUMOylated) or VEGFR2-SUMO1 (a form that is constitutively SUMOylated) was expressed in HUVEC by lentivirus infection, and VEGF-induced p-VEGFR2 was examined by western blotting.