Pgrn induces outgrowth independent of Sort1. (A) Western blot analysis of Pgrn and Sort1 levels in WT and Sort1−/− hippocampal cultures. (B) Mouse specific ELISA showing increasing levels of Pgrn in Sort1−/− culture media. (C) Bar graph quantification of normalized total neurite outgrowth in Sort1−/− and WT cultures showing significant decreases in Sort1−/−. (D-G) Normalized total outgrowth (D,F) and total branching (E,G) in Sort1−/− and WT cultures with increasing amounts of His-rPGRN treatment. Data is presented as the mean ± SEM. *p < 0.05; **p < 0.01.