Endogenous EGF up-regulates KOR and axonal marker protein expression in mouse spinal cord. (A) Quantifications of Western blot (densitometry) of EGF, EGFR, pEGFR, KOR, GAP43, TAG-1, Grb7, and Actin from mouse embryos or newborn spinal cords are presented. The data represent the mean ± SEM of quadruple samples. (B) Quantifications of Western blot from control, Gefitinib-treated, or Erlotinib-treated mouse embryo or newborn spinal cords. The data represent the mean ± SEM of quadruple samples, analyzed by two-way ANOVA comparing drug-treated and control (*, P < 0.05). Corresponding Western blots are shown in Fig. S1.