SCN9A and neuroma: Similar to the previous studies investigating MAPK activation in animal models of chronic pain and those focusing on the regulation of Nav1.7 and Nav1.8 by kinases in vitro, ERK1/2 and p38 are increased along with the Nav1.7 and Nav1.8 isoforms in painful human neuromas (Black et al., 2008), where they likely also contribute to neuronal hyperexcitability.