Sensory neuron-specific ERK1/2 double knock-out mice do not develop NGF-induced heat hypersensitivity. A, Following intraplantar injection of 0.2 μg/10 μl NGF, paw withdrawal latency to a radiant heat source was assessed in ERK dKO (n = 8) and ERK2f/f (n = 7) control littermates, and each time point was divided by the baseline paw withdrawal latency to express data as a percentage of the baseline latency. *p < 0.05 (two-way RM ANOVA with Bonferroni post test). B, Percentage of baseline data was averaged from the first 3 h following intraplantar injection of 0.2 μg/10 μl NGF for ERK dKO (n = 8) and their ERK2f/f control littermates (n = 7; unpaired t test). **p < 0.01. A, B, Data are expressed as a mean of the percentage baseline ± SEM.