Dual HVR replacement selectively affects BCR signaling in ABC-DLBCL lines. (A) Calcium flux in response to BCR stimulation in OCI-Ly19 cells with endogenous or TTox-reactive HVRs. BCR cross-linking with anti-IgM triggers calcium flux for both HVR types, but only cells with TTox-reactive HVRs respond to TTox. (B) Absolute growth curves after HVR replacement or BCR KO in GCB-DLBCL lines, relative to the starting point 3 days (SUDHL-6 and OCI-Ly19) or 6 days (OCI-Ly7 and SUDHL-4) after electroporation. Effects of HVR replacement are similar for endogenous (WT) and TTox-reactive HVRs. (C) Absolute growth curves after HVR replacement or BCR KO in PTEN-deficient ABC-DLBCL line U2932. Growth reduction by HVR replacement with TTox-reactive HVRs (upper panel) or U2932 reverted HVRs in a separate experiment (lower panel) is similar to that of BCR KO. (D) Absolute growth curves after HVR replacement or BCR KO in PTEN-expressing ABC-DLBCL line HBL-1. Growth reduction by HVR replacement with TTox-reactive HVRs is less than that of BCR KO (upper panel) in otherwise unmodified HBL-1 cells, but similar to that of BCR KO in HBL-1 cells in which CD79A ITAM tyrosines have been mutated (lower panel). Panels B-D show the mean ± SD from 3 biological replicates.