The expression of S-100 and cellularity at four weeks after crush injury. (a) At four weeks after crush injury, specimens from both sem (p38+/−) and wt (p38+/+) mice were processed for immunostaining using anti S-100 antibody. Scale bar indicates 50 μm. (b) Cellularity was evaluated by counting the number of cells per microscopic field and expressed as the cell density (N/mm2). Asterisks indicate significant difference between genotypes (**P <0.01).