In vitro, CG neurite outgrowth on laminin-1 and merosin is sensitive to anti-laminin-1 and anti-merosin antibodies, respectively. Dissociated E7.5 CG neurons were plated on laminin-1 (Ln) and merosin (Mn) and allowed to extend neurites for 4–5 hr (Mn) or 9–10 hr (Ln) in the presence of no antibody (0), anti-Mn serum (1:25), normal rabbit serum (NRS; 1:25), or affinity-purified anti-laminin-1 (JW2; 20 μg/ml). Values represent the mean ± SD of 4 determinations from two experiments, each performed in duplicate.