Activity of all JNK isoforms contributes to neurite growth in spiral ganglion neurons

► JNK activity is needed for initial neurite growth and continued growth. ► The effect of JNK inhibition is rapid and rapidly reversible after washout. ► JNK activation kinetics is rapid in growth cones, slow in the soma and nucleus. ► JNK isoforms are present in the nucleus and cytoplasm. ► All three JNK isoforms contribute to promotion of neurite growth.