Wnts Specify LRP6 mAb Activity Figure 4. LRP6 antibody bivalency mediates potentiation of Wnt signaling. (A–D) One-armed (OA) YW211.31 antibody retains inhibitory activity similar in potency to the whole IgG against Wnt3a-induced signaling in Hs578T cells stably integrated with Wnt luciferase reporter (B) and against autocrine Wnt signaling in PA-1 cells transfected with reporter (D). The one-armed antibody lacks the potentiating effect of the intact PLoS ONE | www.plosone.org 8 September 2010 | Volume 5 | Issue 9 | e12682