mAb #113-115 selectively reduced GABAergic signaling in vitro, independent of receptor internalization. (A and B) Representative traces from evoked (A) or GABA-dependent (B) currents of murine autaptic neurons after preincubation with indicated human mAb. (C–F) Amplitudes of evoked or chemically induced responses (C) to GABA (D), kainite (E), or NMDA (F) of murine autaptic neurons after mAb preincubation as indicated (values normalized to mean of untreated condition). Data were analyzed using Kruskal-Wallis, Dunn’s post hoc tests (**, P ≤ 0.01; ****, P ≤ 0.0001; or not shown when P > 0.05). Each dot represents one neuron, n = 25 per condition. Bars indicate mean ± SEM. (G–J) Quantifications of the indicated total (G and H) and biotinylated surface (I and J) proteins from cultured neocortical rat neurons as analyzed by Western blotting (values normalized to N-Cadherin expression and mean of untreated condition). Each dot represents one preparation after mAb treatment, n = 11 per condition from four separate neuronal cultures. Bars indicate mean ± SEM.