RET is a receptor tyrosine kinase for GDNF-family proteins. RET is involved in neuronal development and maintenance in the nervous system, as well as neural crest cell migration and the development of the enteric nervous system. It is mutated in a wide range of cancers and in Hirschsprung’s disease. It has been found to be downregulated after ischemic injury in the brain, which in turn results in a decrease in GDNF protein and its neuroprotective effects and which may worsen the effects of cerebral trauma. In immunohistochemistry, RET has membranous and cytoplasmic positivity in most tissues throughout the body. References: Cell Death Dis. 2015 Feb; 6(2): e1645, PMID: 25675305; Sci Rep. 2015; 5: 13109, PMID: 26300345