Rac1 is necessary for KSHV-induced VE-cadherin and β-catenin phosphorylation. (A) HUVEC and KSHV-HUVEC were transfected for 48 hours with control siRNA or siRNA targeting Rac1 and then lysed. VE-cadherin was immunoprecipitated with anti–VE-cadherin antibody and analyzed by Western blot using anti-phosphotyrosine antibody (clone 4G10). The phosphorylated forms of VE-cadherin were analyzed by immunoblotting using antibodies that specifically recognize VE-cadherin phosphorylated at Tyr-731 (Y731). Total VE-cadherin was used as a loading control. (B) HUVEC and KSHV-HUVEC were transfected for 48 hours with control siRNA or siRNA targeting Rac1 and then lysed. Lysates were analyzed by Western blot for phosphorylated forms of β-catenin using antibodies that specifically recognize β-catenin phosphorylated at Tyr-654 (Y654). Total β-catenin was used as a loading control.