Activation of Rho signaling by mutant RHPN2 proteins. (A) Mutation needle plots of RHPN2 in EBV⁺-DLBL. The mutations found in the 5 EBV⁺-DLBLs of 29 cases sequenced are shown. BRO1, yeast Bro1 homology domain; HR1, protein kinase C-related kinase homology region 1 domain. (B) Protein levels of wild-type and mutant RHPN2 when mRNA levels were normalized. (C) Protein stability of wild-type and mutant RHPN2. The protein levels of each mutant RHPN2 were evaluated after 3 hours of treatment with cycloheximide (100 μg/mL). (D) Rho activity of wild-type and mutant RHPN2. Rho activity were assessed by a GST-RBD-Rhotekin pull-down assay, and the RHPN2 mutations were associated with increased Rho activity.