NGFR and thyroid cancer: In thyroid cancer, in addition to proNGF overexpression [10], the upregulation of proNGF/NGF receptors (the tyrosine kinase TrkA, the neurotrophin receptor p75NTR and the pro-neurotrophin receptor sortilin) has been reported [17], suggesting a role for proNGF in thyroid carcinogenesis and a potential value as a diagnostic or prognostic biomarker.