Fig. 2. Nerve growth factor (NGF) expression in incised or sham-operated plantar flexor digitorum brevis muscle. (  A ) Changes in NGF messenger RNA (mRNA) relative to β-actin mRNA examined by real-time quantitative-polymerase chain reaction. Data are expressed as mean ± SEM of ratio of incised flexor muscle to sham controls. (  B ) NGF protein determined by enzyme-linked immunosorbent assay. Data are shown as mean ± SEM of nanogram of NGF protein per milligram of protein. (  C ) Western blots for NGF and actin immunoreactivity. Top: Example of Western blot showing immunoreactive NGF and actin control bands in detailed time course after plantar incision. Bottom: Summary of relative changes in NGF protein expression after plantar incision. Data are expressed as mean ± SEM of ratio of incised flexor muscle to sham controls. Non = contralateral nonincised muscle. PO = post operative. POD = postoperative day. *  P < 0.05, **  P < 0.01  versus sham. N = 6 per group.