Fig. 6. Effect of NRP/B and its mutants on neuronal differentiation. (A) PC12 cells were grown in 10% serum as a control (left) or stimulated with NGF (right). (B) PC12 cells were transfected with either 1 µg NRP/B (WT) or NRP/B mutant, or with control GFP vector (pEGFP). Spontaneous neurite outgrowth 3 days after transfection was observed by green fluorescence using UV microscopy. The experiments were repeated at least three times. BTB mtA, BTB mutant A. (C) Quantitative analyses of neurite outgrowth in PC12 cells transfected with NRP/B and mutant NRP/B: the NRP/B-BTB domain and NRP/B-BTB mtA. The percentage of cells with neurites was calculated in representative experiments repeated three times. Data are means±s.d. Bars, 10 µm.