NOS1AP increases processes outgrowth and influences Rac activity. A–D, Epifluorescent images of dissociated hippocampal neurons cultured for 13 DIV and then transfected with YFP (A), YFP-NOS1AP (B), YFP-NOS1AP PTB (C), or YFP-NOS1APΔPTB (D). Scale bar, 5 μm. E, Quantification of the number of processes per 50 μm segment of dendrite in YFP (n = 122), YFP-NOS1AP (n = 87), YFP-NOS1AP PTB (n = 17), and YFP-NOS1APΔPTB (n = 18). F, HEK293T cells were transfected as indicated. Cleared lysates were incubated with GST-PBD and then probed with anti-Rac to determine the amount of activated Rac (upper panel). GTPγS was included as a positive control. Whole-cell lysate from the transfected cells was probed with anti-Rac (lower panel). G, Quantification of activated Rac. An increase in Rac activity was seen in YFP-NOS1AP (n = 5) and YFP-NOS1AP PTB (n = 5) relative to YFP alone (n = 5). ***p < 0.0001; *p < 0.05.