FIGURE 5.

Intracellular cleavage of proNGF is not required for MAPK phosphorylation. PC12 cells were incubated with 50 μm furin inhibitor (FI) 1 h before treating them with either cleavage-resistant proNGF or WT-NGF as described under “Experimental Procedures.” Controls were treated similarly but without furin inhibitor. Cells were treated with proNGFhis or WT-NGFhis for 5 min (A) or 1 h (B) before harvesting and Western blotting for p-MAPK and MAPK. C, Western blotting for NGF showed less processing of cleavable WT-NGF to mature NGF in cells treated with FI than in cells not treated with FI.