(A) Schematic of the L1 domain swaps CFLCCC and FCSFFF. (B) Images of living cortical neurons cotransfected with mRuby-Lifeact and EGFP-labeled protein or chimera at 12 h postplating. (C–F) Quantification of stage 1 neurons, comparing the effects of the L1 swap constructs on peripheral intensity (C), filopodia number (D), cell complexity (E), and tubule number (F) at 12 h postplating. CIP4S-EGFP (n = 24 cells), CFLCCC-EGFP (n = 47 cells), FBP17L-EGFP (n = 23 cells), or FCSFFF-EGFP (n = 37 cells). (G) Stacked bar graph comparing the percentage of neurons in stage (st) 1, 2, and 3 for neurons expressing CIP4S-EGFP (n = 45) versus CFLCCC-EGFP (n = 72) and FBP17L-EGFP (n = 49) versus FCSFFF-EGFP (n = 68) at 12 h postplating. Two-way ANOVA with Bonferroni post-test multiple comparison. *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001; ns, not significant. Scale bar represents 5 µm in whole-cell images and 1 µm in insets.