Receptor tyrosine-protein kinase involved in numerous cellular mechanisms including cell proliferation, neuronal navigation, cell migration, and cell differentiation upon binding with glial cell derived neurotrophic factor family ligands. Phosphorylates PTK2/FAK1. Regulates both cell death/survival balance and positional information. Required for the molecular mechanisms orchestration during intestine organogenesis; involved in the development of enteric nervous system and renal organogenesis during embryonic life, and promotes the formation of Peyer's patch-like structures, a major component of the gut-associated lymphoid tissue. Modulates cell adhesion via its cleavage by caspase in sympathetic neurons and mediates cell migration in an integrin (e.g. ITGB1 and ITGB3)-dependent manner. Involved in the development of the neural crest. Active in the absence of ligand, triggering apoptosis through a mechanism that requires receptor intracellular caspase cleavage. Acts as a dependence receptor; in the presence of the ligand GDNF in somatotrophs (within pituitary), promotes survival and down regulates growth hormone (GH) production, but triggers apoptosis in absence of GDNF. Regulates nociceptor survival and size. Triggers the differentiation of rapidly adapting (RA) mechanoreceptors. Mediator of several diseases such as neuroendocrine cancers; these diseases are characterized by aberrant integrins-regulated cell migration (By similarity). Mediates, through interaction with GDF15-receptor GFRAL, GDF15-induced cell-signaling in the brainstem which induces inhibition of food-intake. Activates MAPK- and AKT-signaling pathways (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Phosphorylated form interacts with the PBT domain of DOK2, DOK4 and DOK5 (By similarity). The phosphorylated form interacts with PLCG1 and GRB7 (By similarity). Interacts (not phosphorylated) with PTK2/FAK1 (via FERM domain) (By similarity). Extracellular cell-membrane anchored RET cadherin fragments form complex in neurons with reduced trophic status, preferentially at the contact sites between somas (By similarity). Interacts with AIP in the pituitary gland; this interaction prevents the formation of the AIP-survivin complex (By similarity). Binds to ARTN (By similarity). Interacts (inactive) with CBLC and CD2AP; dissociates upon activation by GDNF which increases CBLC:CD2AP interaction (PubMed:18753381). Interacts (via the extracellular domain) with GFRAL (via the extracellular domain); the interaction mediates cellular signaling upon interaction of GFRAL with its ligand GDF15. Interaction with GFRAL requires previous GDF15-binding to GFRAL (By similarity). Interacts with GFRA1; in the presence of SORL1, the GFRA1/RET complex is targeted to endosomes (PubMed:23333276). Interacts with GFRA1; in the presence of SORL1, the GFRA1/RET complex is targeted to endosomes (PubMed:23333276). Interacts with GDNF (By similarity). Predominantly located on the plasma membrane. In the presence of SORL1 and GFRA1, directed to endosomes. Expressed in neurons and kidney glomeruli podocytes (at protein level) (PubMed:18753381). Detected at least in colon, duodenum, adipose tissue, heart, jejenum, lung, muscle, spleen, stomac, testis and thymus (PubMed:28846099). Autophosphorylated on C-terminal tyrosine residues upon ligand stimulation. Dephosphorylated by PTPRJ on Tyr-906, Tyr-1016 and Tyr-1063 (By similarity). Proteolytically cleaved by caspase-3. The soluble RET kinase fragment is able to induce cell death. The extracellular cell-membrane anchored RET cadherin fragment accelerates cell adhesion in sympathetic neurons (By similarity). Belongs to the protein kinase superfamily. Tyr protein kinase family.