The frequent occurrence of RET rearrangements in papillary carcinoma (Elisei et al, 2001; Soares et al, 2003) and the recent observation that a consistent number of nonrearranged cases have an activating mutation of BRAF that also cause signal transduction through the RET–RAS pathway (Fukushima et al, 2003) are consistent with the possibility that dysregulation of MET transcription is caused by the genetic transforming alterations specifically associated with this histotype. This evidence concerns the gene RET and papillary carcinoma.