A study of papillary thyroid cancer (PTC) biopsies in 2001 identified different splice variants in the RET extracellular domain described as in-frame changes with preservation of the tyrosine kinase domain (RET 1/8, RET 2/8, RET 3/8) (Fluge et al., 2001). Here, RET is linked to thyroid gland papillary carcinoma.