FOS and neuritis: For example, increased levels of pERK still persist 7 days after injection of complete Freund’s adjuvant (CFA) into the hind paw (Adwanikar et al., 2004), whereas a study in a neuritis model (Kominato et al., 2003) demonstrated that pERK (and Fos) was not increased in animals with neuritis alone but, following noxious stimulation (pinch) 3 and 7 days after induction of neuritis, levels of pERK (and Fos) were greater in animals with neuritis than in control animals.